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curl(1)                           Curl Manual                          curl(1)




NAME

       curl - transfer a URL


SYNOPSIS

       curl [options / URLs]


DESCRIPTION

       curl  is  a tool to transfer data from or to a server, using one of the
       supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS,  IMAP,
       IMAPS,  LDAP,  LDAPS,  MQTT, POP3, POP3S, RTMP, RTMPS, RTSP, SCP, SFTP,
       SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). The command  is  designed  to
       work without user interaction.

       curl offers a busload of useful tricks like proxy support, user authen-
       tication, FTP upload, HTTP post, SSL connections, cookies, file  trans-
       fer  resume,  Metalink,  and more. As you will see below, the number of
       features will make your head spin!

       curl is powered by  libcurl  for  all  transfer-related  features.  See
       libcurl(3) for details.


URL

       The  URL  syntax is protocol-dependent. You'll find a detailed descrip-
       tion in RFC 3986.

       You can specify multiple URLs or parts of URLs  by  writing  part  sets
       within braces and quoting the URL as in:

         "http://site.{one,two,three}.com"

       or you can get sequences of alphanumeric series by using [] as in:

         "ftp://ftp.example.com/file[1-100].txt"

         "ftp://ftp.example.com/file[001-100].txt"    (with leading zeros)

         "ftp://ftp.example.com/file[a-z].txt"

       Nested  sequences  are not supported, but you can use several ones next
       to each other:

         "http://example.com/archive[1996-1999]/vol[1-4]/part{a,b,c}.html"

       You can specify any amount of URLs on the command line.  They  will  be
       fetched  in a sequential manner in the specified order. You can specify
       command line options and URLs mixed and in any  order  on  the  command
       line.

       You  can  specify a step counter for the ranges to get every Nth number
       or letter:

         "http://example.com/file[1-100:10].txt"

         "http://example.com/file[a-z:2].txt"

       When using [] or {} sequences when invoked from a command line  prompt,
       you probably have to put the full URL within double quotes to avoid the
       shell from interfering with it. This also  goes  for  other  characters
       treated special, like for example '&', '?' and '*'.

       Provide  the IPv6 zone index in the URL with an escaped percentage sign
       and the interface name. Like in

         "http://[fe80::3%25eth0]/"

       If you specify URL without protocol:// prefix,  curl  will  attempt  to
       guess  what  protocol  you might want. It will then default to HTTP but
       try other protocols based on often-used host name prefixes.  For  exam-
       ple,  for  host names starting with "ftp." curl will assume you want to
       speak FTP.

       curl will do its best to use what you pass to it as a URL.  It  is  not
       trying  to  validate it as a syntactically correct URL by any means but
       is instead very liberal with what it accepts.

       curl will attempt to re-use connections for multiple file transfers, so
       that  getting many files from the same server will not do multiple con-
       nects / handshakes. This improves speed. Of course this is only done on
       files  specified  on  a  single command line and cannot be used between
       separate curl invokes.


OUTPUT

       If not told otherwise, curl writes the received data to stdout. It  can
       be  instructed  to  instead save that data into a local file, using the
       -o, --output or -O, --remote-name options. If curl  is  given  multiple
       URLs  to  transfer  on  the  command  line, it similarly needs multiple
       options for where to save them.

       curl does not parse or otherwise "understand" the content  it  gets  or
       writes  as  output.  It does no encoding or decoding, unless explicitly
       asked so with dedicated command line options.


PROTOCOLS

       curl supports numerous protocols, or put in URL  terms:  schemes.  Your
       particular build may not support them all.

       DICT   Lets you lookup words using online dictionaries.

       FILE   Read  or  write  local  files.  curl  does not support accessing
              file:// URL remotely, but  when  running  on  Microsoft  Windows
              using the native UNC approach will work.

       FTP(S) curl  supports  the  File Transfer Protocol with a lot of tweaks
              and levers. With or without using TLS.

       GOPHER Retrieve files.

       HTTP(S)
              curl supports HTTP with numerous options and variations. It  can
              speak  HTTP  version  0.9,  1.0, 1.1, 2 and 3 depending on build
              options and the correct command line options.

       IMAP(S)
              Using the mail reading protocol, curl can "download" emails  for
              you. With or without using TLS.

       LDAP(S)
              curl can do directory lookups for you, with or without TLS.

       MQTT   curl supports MQTT version 3. Downloading over MQTT equals "sub-
              scribe" to a topic while uploading/posting equals "publish" on a
              topic.  MQTT  support  is experimental and TLS based MQTT is not
              supported (yet).

       POP3(S)
              Downloading from a pop3 server means getting  a  mail.  With  or
              without using TLS.

       RTMP(S)
              The  Realtime  Messaging  Protocol  is  primarily used to server
              streaming media and curl can download it.

       RTSP   curl supports RTSP 1.0 downloads.

       SCP    curl supports SSH version 2 scp transfers.

       SFTP   curl supports SFTP (draft 5) done over SSH version 2.

       SMB(S) curl supports SMB version 1 for upload and download.

       SMTP(S)
              Uploading contents to an SMTP server  means  sending  an  email.
              With or without TLS.

       TELNET Telling curl to fetch a telnet URL starts an interactive session
              where it sends what it reads  on  stdin  and  outputs  what  the
              server sends it.

       TFTP   curl can do TFTP downloads and uploads.


PROGRESS METER

       curl  normally  displays a progress meter during operations, indicating
       the amount of transferred data,  transfer  speeds  and  estimated  time
       left,  etc.  The progress meter displays number of bytes and the speeds
       are in bytes per second. The suffixes (k, M, G, T, P) are  1024  based.
       For example 1k is 1024 bytes. 1M is 1048576 bytes.

       curl  displays  this  data to the terminal by default, so if you invoke
       curl to do an operation and it is about to write data to the  terminal,
       it disables the progress meter as otherwise it would mess up the output
       mixing progress meter and response data.

       If you want a progress meter for HTTP POST or PUT requests, you need to
       redirect  the  response output to a file, using shell redirect (>), -o,
       --output or similar.

       It is not the same case for FTP upload as that operation does not  spit
       out any response data to the terminal.

       If  you  prefer  a  progress  "bar"  instead  of the regular meter, -#,
       --progress-bar is your friend. You can also disable the progress  meter
       completely with the -s, --silent option.


OPTIONS

       Options  start  with  one or two dashes. Many of the options require an
       additional value next to them.

       The short "single-dash" form of the options, -d  for  example,  may  be
       used with or without a space between it and its value, although a space
       is a recommended separator. The long "double-dash" form, -d, --data for
       example, requires a space between it and its value.

       Short version options that don't need any additional values can be used
       immediately next to each other, like for example you  can  specify  all
       the options -O, -L and -v at once as -OLv.

       In general, all boolean options are enabled with --option and yet again
       disabled with --no-option. That is, you use the exact same option  name
       but prefix it with "no-". However, in this list we mostly only list and
       show the --option version of them. (This concept with --no options  was
       added  in  7.19.0.  Previously  most  options  were  toggled  on/off on
       repeated use of the same command line option.)

       --abstract-unix-socket <path>
              (HTTP) Connect through an abstract Unix domain  socket,  instead
              of  using  the  network.   Note:  netstat  shows  the path of an
              abstract socket prefixed with '@', however the  <path>  argument
              should not have this leading character.

              Added in 7.53.0.

       --alt-svc <file name>
              (HTTPS) WARNING: this option is experimental. Do not use in pro-
              duction.

              This option enables the alt-svc parser in curl. If the file name
              points  to  an  existing  alt-svc cache file, that will be used.
              After a completed transfer, the cache will be saved to the  file
              name again if it has been modified.

              Specify a "" file name (zero length) to avoid loading/saving and
              make curl just handle the cache in memory.

              If this option is used several times, curl  will  load  contents
              from all the files but the last one will be used for saving.

              Added in 7.64.1.

       --anyauth
              (HTTP) Tells curl to figure out authentication method by itself,
              and use the most secure one the remote site claims  to  support.
              This is done by first doing a request and checking the response-
              headers, thus possibly inducing  an  extra  network  round-trip.
              This  is  used  instead  of  setting  a  specific authentication
              method, which you can do with  --basic,  --digest,  --ntlm,  and
              --negotiate.

              Using --anyauth is not recommended if you do uploads from stdin,
              since it may require data to be sent twice and then  the  client
              must  be able to rewind. If the need should arise when uploading
              from stdin, the upload operation will fail.

              Used together with -u, --user.

              See also --proxy-anyauth, --basic and --digest.

       -a, --append
              (FTP SFTP) When used in an upload, this makes curl append to the
              target  file  instead  of  overwriting  it.  If  the remote file
              doesn't exist, it will be  created.   Note  that  this  flag  is
              ignored by some SFTP servers (including OpenSSH).

       --aws-sigv4 <provider1[:provider2[:region[:service]]]>
              Use AWS V4 signature authentication in the transfer.

              The  provider argument is a string that is used by the algorithm
              when creating outgoing authentication headers.

              The region argument is a string that points to a geographic area
              of  a resources collection (region-code) when the region name is
              omitted from the endpoint.

              The service argument is a string that points to a function  pro-
              vided by a cloud (service-code) when the service name is omitted
              from the endpoint.

              Added in 7.75.0.

       --basic
              (HTTP) Tells curl to use  HTTP  Basic  authentication  with  the
              remote  host.  This  is  the  default and this option is usually
              pointless, unless you use it to override a previously set option
              that  sets  a  different  authentication method (such as --ntlm,
              --digest, or --negotiate).

              Used together with -u, --user.

              See also --proxy-basic.

       --cacert <file>
              (TLS) Tells curl to use the specified certificate file to verify
              the  peer.  The  file  may contain multiple CA certificates. The
              certificate(s) must be in PEM format. Normally curl is built  to
              use a default file for this, so this option is typically used to
              alter that default file.

              curl recognizes the environment variable named  'CURL_CA_BUNDLE'
              if  it  is  set,  and uses the given path as a path to a CA cert
              bundle. This option overrides that variable.

              The windows version of curl will automatically  look  for  a  CA
              certs file named 'curl-ca-bundle.crt', either in the same direc-
              tory as curl.exe, or in the Current Working Directory, or in any
              folder along your PATH.

              If  curl  is  built  against  the  NSS  SSL library, the NSS PEM
              PKCS#11 module (libnsspem.so) needs to  be  available  for  this
              option to work properly.

              (iOS  and macOS only) If curl is built against Secure Transport,
              then this option is supported for  backward  compatibility  with
              other  SSL  engines,  but it should not be set. If the option is
              not set, then curl will use the certificates in the  system  and
              user  Keychain to verify the peer, which is the preferred method
              of verifying the peer's certificate chain.

              (Schannel only) This option is supported for Schannel in Windows
              7  or later with libcurl 7.60 or later. This option is supported
              for backward compatibility with other SSL engines; instead it is
              recommended  to  use  Windows'  store  of root certificates (the
              default for Schannel).

              If this option is used several times, the last one will be used.

       --capath <dir>
              (TLS)  Tells  curl to use the specified certificate directory to
              verify the peer. Multiple paths can be  provided  by  separating
              them with ":" (e.g.  "path1:path2:path3"). The certificates must
              be in PEM format, and if curl  is  built  against  OpenSSL,  the
              directory  must  have  been processed using the c_rehash utility
              supplied with OpenSSL. Using --capath can allow  OpenSSL-powered
              curl  to  make  SSL-connections much more efficiently than using
              --cacert if the --cacert file contains many CA certificates.

              If this option is set, the default capath value will be ignored,
              and if it is used several times, the last one will be used.

       --cert-status
              (TLS)  Tells curl to verify the status of the server certificate
              by using the Certificate Status Request (aka. OCSP stapling) TLS
              extension.

              If  this option is enabled and the server sends an invalid (e.g.
              expired) response, if the response suggests that the server cer-
              tificate  has  been  revoked, or no response at all is received,
              the verification fails.

              This is currently only implemented in the  OpenSSL,  GnuTLS  and
              NSS backends.

              Added in 7.41.0.

       --cert-type <type>
              (TLS)  Tells  curl  what type the provided client certificate is
              using. PEM, DER, ENG and P12 are recognized types.  If not spec-
              ified, PEM is assumed.

              If this option is used several times, the last one will be used.

              See also -E, --cert, --key and --key-type.

       -E, --cert <certificate[:password]>
              (TLS) Tells curl to use the specified  client  certificate  file
              when getting a file with HTTPS, FTPS or another SSL-based proto-
              col. The certificate must be in PKCS#12 format if  using  Secure
              Transport,  or  PEM  format  if  using any other engine.  If the
              optional password isn't specified, it will be queried for on the
              terminal.  Note  that  this  option assumes a "certificate" file
              that is the private key and the client certificate concatenated!
              See -E, --cert and --key to specify them independently.

              If  curl  is  built against the NSS SSL library then this option
              can tell curl the nickname of the certificate to use within  the
              NSS  database defined by the environment variable SSL_DIR (or by
              default /etc/pki/nssdb). If the NSS  PEM  PKCS#11  module  (lib-
              nsspem.so)  is  available  then  PEM files may be loaded. If you
              want to use a file from the current directory, please precede it
              with  "./"  prefix, in order to avoid confusion with a nickname.
              If the nickname contains ":", it needs to be preceded by "\"  so
              that  it  is not recognized as password delimiter.  If the nick-
              name contains "\", it needs to be escaped as "\\" so that it  is
              not recognized as an escape character.

              If  curl is built against OpenSSL library, and the engine pkcs11
              is available, then a PKCS#11 URI (RFC 7512) can be used to spec-
              ify  a  certificate located in a PKCS#11 device. A string begin-
              ning with "pkcs11:" will be interpreted as a PKCS#11 URI.  If  a
              PKCS#11 URI is provided, then the --engine option will be set as
              "pkcs11" if none was provided and the --cert-type option will be
              set as "ENG" if none was provided.

              (iOS  and macOS only) If curl is built against Secure Transport,
              then the certificate string can either be the name of a certifi-
              cate/private  key in the system or user keychain, or the path to
              a PKCS#12-encoded certificate and private key. If  you  want  to
              use  a  file  from the current directory, please precede it with
              "./" prefix, in order to avoid confusion with a nickname.

              (Schannel only) Client certificates must be specified by a  path
              expression  to  a  certificate  store.  (Loading PFX is not sup-
              ported; you can import it to a store first). You can use "<store
              location>\<store  name>\<thumbprint>"  to refer to a certificate
              in  the  system  certificates  store,  for   example,   "Curren-
              tUser\MY\934a7ac6f8a5d579285a74fa61e19f23ddfe8d7a".   Thumbprint
              is usually a SHA-1 hex string which you can see  in  certificate
              details.  Following  store locations are supported: CurrentUser,
              LocalMachine, CurrentService, Services,  CurrentUserGroupPolicy,
              LocalMachineGroupPolicy, LocalMachineEnterprise.

              If this option is used several times, the last one will be used.

              See also --cert-type, --key and --key-type.

       --ciphers <list of ciphers>
              (TLS) Specifies which ciphers to use in the connection. The list
              of  ciphers  must  specify  valid ciphers. Read up on SSL cipher
              list details on this URL:

               https://curl.se/docs/ssl-ciphers.html

              If this option is used several times, the last one will be used.

       --compressed-ssh
              (SCP SFTP) Enables built-in SSH compression.  This is a request,
              not an order; the server may or may not do it.

              Added in 7.56.0.

       --compressed
              (HTTP) Request a compressed response using one of the algorithms
              curl supports, and automatically decompress the content. Headers
              are not modified.

              If this option is used  and  the  server  sends  an  unsupported
              encoding, curl will report an error.

       -K, --config <file>

              Specify  a  text  file  to read curl arguments from. The command
              line arguments found in the text file will be used  as  if  they
              were provided on the command line.

              Options  and their parameters must be specified on the same line
              in the file, separated by whitespace, colon, or the equals sign.
              Long  option  names  can  optionally be given in the config file
              without the initial double dashes and if so, the colon or equals
              characters can be used as separators. If the option is specified
              with one or two dashes, there can be no colon or equals  charac-
              ter between the option and its parameter.

              If  the  parameter  contains whitespace (or starts with : or =),
              the parameter must be  enclosed  within  quotes.  Within  double
              quotes,  the  following  escape sequences are available: \\, \",
              \t, \n, \r and \v. A backslash preceding  any  other  letter  is
              ignored.  If  the first column of a config line is a '#' charac-
              ter, the rest of the line will be treated  as  a  comment.  Only
              write one option per physical line in the config file.

              Specify  the  filename  to -K, --config as '-' to make curl read
              the file from stdin.

              Note that to be able to specify a URL in the  config  file,  you
              need  to  specify  it  using the --url option, and not by simply
              writing the URL on its own line. So, it could  look  similar  to
              this:

              url = "https://curl.se/docs/"

              When  curl  is invoked, it (unless -q, --disable is used) checks
              for a default config file and uses it if found. The default con-
              fig file is checked for in the following places in this order:

              1) Use the CURL_HOME environment variable if set

              2) Use the XDG_CONFIG_HOME environment variable if set (Added in
              7.73.0)

              3) Use the HOME environment variable if set

              4) Non-windows: use getpwuid to find the home directory

              5) Windows: use APPDATA if set

              6) Windows: use "USERPROFILE0lication Data" if set

              7) On windows, if there is no .curlrc file in the home  dir,  it
              checks for one in the same dir the curl executable is placed. On
              Unix-like systems, it will simply try to load .curlrc  from  the
              determined home dir.

              # --- Example file ---
              # this is a comment
              url = "example.com"
              output = "curlhere.html"
              user-agent = "superagent/1.0"

              # and fetch another URL too
              url = "example.com/docs/manpage.html"
              -O
              referer = "http://nowhereatall.example.com/"
              # --- End of example file ---

              This  option  can be used multiple times to load multiple config
              files.

       --connect-timeout <seconds>
              Maximum time in seconds that  you  allow  curl's  connection  to
              take.   This  only  limits the connection phase, so if curl con-
              nects within the given period it will continue - if not it  will
              exit.  Since version 7.32.0, this option accepts decimal values.

              If this option is used several times, the last one will be used.

              See also -m, --max-time.

       --connect-to <HOST1:PORT1:HOST2:PORT2>

              For  a  request  to  the  given  HOST1:PORT1  pair,  connect  to
              HOST2:PORT2 instead.  This option is suitable to direct requests
              at a specific server, e.g. at a specific cluster node in a clus-
              ter of servers. This option is only used to establish  the  net-
              work  connection.  It  does NOT affect the hostname/port that is
              used for TLS/SSL (e.g. SNI, certificate verification) or for the
              application  protocols.  "HOST1"  and  "PORT1"  may be the empty
              string, meaning "any host/port". "HOST2" and "PORT2" may also be
              the   empty   string,   meaning   "use  the  request's  original
              host/port".

              A "host" specified to this option is compared as a string, so it
              needs  to  match  the name used in request URL. It can be either
              numerical such as "127.0.0.1" or the  full  host  name  such  as
              "example.org".

              This option can be used many times to add many connect rules.

              See also --resolve and -H, --header. Added in 7.49.0.

       -C, --continue-at <offset>
              Continue/Resume  a  previous  file transfer at the given offset.
              The given offset is the exact  number  of  bytes  that  will  be
              skipped,  counting  from the beginning of the source file before
              it is transferred to the destination.  If used with uploads, the
              FTP server command SIZE will not be used by curl.

              Use  "-C  -" to tell curl to automatically find out where/how to
              resume the transfer. It then uses the given  output/input  files
              to figure that out.

              If this option is used several times, the last one will be used.

              See also -r, --range.

       -c, --cookie-jar <filename>
              (HTTP) Specify to which file you want curl to write all  cookies
              after  a  completed  operation. Curl writes all cookies from its
              in-memory cookie storage to the given file at the end of  opera-
              tions.  If  no  cookies  are known, no data will be written. The
              file will be written using the Netscape cookie file  format.  If
              you set the file name to a single dash, "-", the cookies will be
              written to stdout.

              This command line option will activate the  cookie  engine  that
              makes curl record and use cookies. Another way to activate it is
              to use the -b, --cookie option.

              If the cookie jar can't be created or written to, the whole curl
              operation  won't fail or even report an error clearly. Using -v,
              --verbose will get a warning displayed, but  that  is  the  only
              visible feedback you get about this possibly lethal situation.

              If  this  option  is used several times, the last specified file
              name will be used.

       -b, --cookie <data|filename>
              (HTTP) Pass the data to the HTTP server in the Cookie header. It
              is  supposedly the data previously received from the server in a
              "Set-Cookie:"  line.   The  data  should  be   in   the   format
              "NAME1=VALUE1; NAME2=VALUE2".

              If  no '=' symbol is used in the argument, it is instead treated
              as a filename to read previously stored cookie from. This option
              also  activates  the  cookie  engine which will make curl record
              incoming cookies, which may be handy if  you're  using  this  in
              combination  with  the  -L, --location option or do multiple URL
              transfers on the same invoke. If the  file  name  is  exactly  a
              minus ("-"), curl will instead read the contents from stdin.

              The file format of the file to read cookies from should be plain
              HTTP headers (Set-Cookie style) or the  Netscape/Mozilla  cookie
              file format.

              The  file  specified with -b, --cookie is only used as input. No
              cookies will be written to the file. To store cookies,  use  the
              -c, --cookie-jar option.

              If you use the Set-Cookie file format and don't specify a domain
              then the cookie is not sent since the domain will  never  match.
              To  address  this,  set  a domain in Set-Cookie line (doing that
              will include sub-domains) or preferably: use the  Netscape  for-
              mat.

              This option can be used multiple times.

              Users very often want to both read cookies from a file and write
              updated cookies back to a file, so using both -b,  --cookie  and
              -c, --cookie-jar in the same command line is common.

       --create-dirs
              When used in conjunction with the -o, --output option, curl will
              create the necessary local directory hierarchy as  needed.  This
              option  creates the dirs mentioned with the -o, --output option,
              nothing else. If the --output file name uses no dir  or  if  the
              dirs it mentions already exist, no dir will be created.

              Created dirs are made with mode 0750 on unix style file systems.

              To create remote directories when using FTP or SFTP, try  --ftp-
              create-dirs.

       --create-file-mode <mode>
              (SFTP SCP FILE) When curl is used to create files remotely using
              one of the supported protocols, this option allows the  user  to
              set which 'mode' to set on the file at creation time, instead of
              the default 0644.

              This option takes an octal number as argument.

              See also --ftp-create-dirs. Added in 7.75.0.

       --crlf (FTP SMTP)  Convert  LF  to  CRLF  in  upload.  Useful  for  MVS
              (OS/390).

              (SMTP added in 7.40.0)

       --crlfile <file>
              (TLS) Provide a file using PEM format with a Certificate Revoca-
              tion List that may specify peer certificates that are to be con-
              sidered revoked.

              If this option is used several times, the last one will be used.

              Added in 7.19.7.

       --curves <algorithm list>
              (TLS) Tells curl to request specific curves to  use  during  SSL
              session  establishment  according  to  RFC  8422, 5.1.  Multiple
              algorithms can be provided by separating  them  with  ":"  (e.g.
              "X25519:P-521").   The parameter is available identically in the
              "openssl s_client/s_server" utilities.

              --curves allows a OpenSSL powered curl to  make  SSL-connections
              with  exactly  the  (EC) curve requested by the client, avoiding
              intransparent client/server negotiations.

              If this option is  set,  the  default  curves  list  built  into
              openssl will be ignored.

              Added in 7.73.0.

       --data-ascii <data>
              (HTTP) This is just an alias for -d, --data.

       --data-binary <data>
              (HTTP)  This  posts data exactly as specified with no extra pro-
              cessing whatsoever.

              If you start the data with the letter @, the rest  should  be  a
              filename.   Data  is  posted  in  a similar manner as -d, --data
              does, except that newlines and carriage  returns  are  preserved
              and conversions are never done.

              Like  -d,  --data the default content-type sent to the server is
              application/x-www-form-urlencoded. If you want the  data  to  be
              treated as arbitrary binary data by the server then set the con-
              tent-type to octet-stream: -H "Content-Type:  application/octet-
              stream".

              If  this  option  is  used several times, the ones following the
              first will append data as described in -d, --data.

       --data-raw <data>
              (HTTP) This posts data similarly to -d, --data but  without  the
              special interpretation of the @ character.

              See also -d, --data. Added in 7.43.0.

       --data-urlencode <data>
              (HTTP)  This posts data, similar to the other -d, --data options
              with the exception that this performs URL-encoding.

              To be CGI-compliant, the <data> part should begin  with  a  name
              followed  by a separator and a content specification. The <data>
              part can be passed to curl using one of the following syntaxes:

              content
                     This will make curl URL-encode the content and pass  that
                     on.  Just  be careful so that the content doesn't contain
                     any = or @ symbols, as that will  then  make  the  syntax
                     match one of the other cases below!

              =content
                     This  will make curl URL-encode the content and pass that
                     on. The preceding = symbol is not included in the data.

              name=content
                     This will make curl URL-encode the content part and  pass
                     that  on.  Note that the name part is expected to be URL-
                     encoded already.

              @filename
                     This will  make  curl  load  data  from  the  given  file
                     (including  any  newlines), URL-encode that data and pass
                     it on in the POST.

              name@filename
                     This will  make  curl  load  data  from  the  given  file
                     (including  any  newlines), URL-encode that data and pass
                     it on in the POST. The  name  part  gets  an  equal  sign
                     appended, resulting in name=urlencoded-file-content. Note
                     that the name is expected to be URL-encoded already.

       See also -d, --data and --data-raw. Added in 7.18.0.

       -d, --data <data>
              (HTTP MQTT) Sends the specified data in a POST  request  to  the
              HTTP server, in the same way that a browser does when a user has
              filled in an HTML form and presses the submit button. This  will
              cause curl to pass the data to the server using the content-type
              application/x-www-form-urlencoded.  Compare to -F, --form.

              --data-raw is almost the same but does not have a special inter-
              pretation  of  the  @ character. To post data purely binary, you
              should instead use the --data-binary option.  To URL-encode  the
              value of a form field you may use --data-urlencode.

              If  any of these options is used more than once on the same com-
              mand line, the data pieces specified  will  be  merged  together
              with  a  separating  &-symbol.  Thus,  using  '-d name=daniel -d
              skill=lousy'  would  generate  a  post  chunk  that  looks  like
              'name=daniel&skill=lousy'.

              If  you  start  the data with the letter @, the rest should be a
              file name to read the data from, or - if you want curl  to  read
              the  data  from  stdin.  Posting data from a file named 'foobar'
              would thus be done with -d, --data @foobar. When -d,  --data  is
              told  to  read  from a file like that, carriage returns and new-
              lines will be stripped out. If you don't want the @ character to
              have a special interpretation use --data-raw instead.

              See  also  --data-binary,  --data-urlencode and --data-raw. This
              option overrides -F, --form and -I,  --head  and  -T,  --upload-
              file.

       --delegation <LEVEL>
              (GSS/kerberos)  Set  LEVEL to tell the server what it is allowed
              to delegate when it comes to user credentials.

              none   Don't allow any delegation.

              policy Delegates if and only if the OK-AS-DELEGATE flag  is  set
                     in  the  Kerberos  service  ticket,  which is a matter of
                     realm policy.

              always Unconditionally allow the server to delegate.

       --digest
              (HTTP) Enables HTTP Digest authentication. This is an  authenti-
              cation  scheme  that  prevents the password from being sent over
              the wire in clear text. Use this in combination with the  normal
              -u, --user option to set user name and password.

              If  this  option  is  used  several times, only the first one is
              used.

              See also -u, --user, --proxy-digest and --anyauth.  This  option
              overrides --basic and --ntlm and --negotiate.

       --disable-eprt
              (FTP) Tell curl to disable the use of the EPRT and LPRT commands
              when doing active FTP transfers. Curl will normally always first
              attempt  to use EPRT, then LPRT before using PORT, but with this
              option, it will use PORT right away. EPRT and  LPRT  are  exten-
              sions  to  the  original  FTP  protocol, and may not work on all
              servers, but they enable more functionality in a better way than
              the traditional PORT command.

              --eprt can be used to explicitly enable EPRT again and --no-eprt
              is an alias for --disable-eprt.

              If the server is accessed using IPv6, this option will  have  no
              effect as EPRT is necessary then.

              Disabling  EPRT only changes the active behavior. If you want to
              switch to passive mode you need to not  use  -P,  --ftp-port  or
              force it with --ftp-pasv.

       --disable-epsv
              (FTP)  (FTP)  Tell  curl  to disable the use of the EPSV command
              when doing passive FTP  transfers.  Curl  will  normally  always
              first  attempt to use EPSV before PASV, but with this option, it
              will not try using EPSV.

              --epsv can be used to explicitly enable EPSV again and --no-epsv
              is an alias for --disable-epsv.

              If  the  server is an IPv6 host, this option will have no effect
              as EPSV is necessary then.

              Disabling EPSV only changes the passive behavior. If you want to
              switch to active mode you need to use -P, --ftp-port.

       -q, --disable
              If  used  as the first parameter on the command line, the curlrc
              config file will not be read and used. See the -K, --config  for
              details on the default config file search path.

       --disallow-username-in-url
              (HTTP)  This  tells  curl  to  exit if passed a url containing a
              username.

              See also --proto. Added in 7.61.0.

       --dns-interface <interface>
              (DNS) Tell curl to send outgoing DNS  requests  through  <inter-
              face>.  This  option is a counterpart to --interface (which does
              not affect DNS). The supplied string must be an  interface  name
              (not an address).

              See  also  --dns-ipv4-addr  and --dns-ipv6-addr. --dns-interface
              requires that the underlying libcurl was  built  to  support  c-
              ares. Added in 7.33.0.

       --dns-ipv4-addr <address>
              (DNS)  Tell  curl  to  bind to <ip-address> when making IPv4 DNS
              requests, so that the DNS requests originate from this  address.
              The argument should be a single IPv4 address.

              See  also  --dns-interface  and --dns-ipv6-addr. --dns-ipv4-addr
              requires that the underlying libcurl was  built  to  support  c-
              ares. Added in 7.33.0.

       --dns-ipv6-addr <address>
              (DNS)  Tell  curl  to  bind to <ip-address> when making IPv6 DNS
              requests, so that the DNS requests originate from this  address.
              The argument should be a single IPv6 address.

              See  also  --dns-interface  and --dns-ipv4-addr. --dns-ipv6-addr
              requires that the underlying libcurl was  built  to  support  c-
              ares. Added in 7.33.0.

       --dns-servers <addresses>
              Set  the  list  of  DNS servers to be used instead of the system
              default.  The list of IP addresses should be separated with com-
              mas. Port numbers may also optionally be given as :<port-number>
              after each IP address.

              --dns-servers requires that the underlying libcurl was built  to
              support c-ares. Added in 7.33.0.

       --doh-cert-status
              (all) Same as --cert-status but used for DOH (DNS-over-HTTPS).

              Added in 7.76.0.

       --doh-insecure
              (all)  Same as -k, --insecure but used for DOH (DNS-over-HTTPS).

              Added in 7.76.0.

       --doh-url <URL>
              (all) Specifies which DNS-over-HTTPS  (DOH)  server  to  use  to
              resolve  hostnames,  instead  of using the default name resolver
              mechanism. The URL must be HTTPS.

              Some SSL options that you set for your transfer  will  apply  to
              DOH  since  the  name  lookups take place over SSL. However, the
              certificate verification settings are not inherited and  can  be
              controlled  separately via --doh-insecure and --doh-cert-status.

              If this option is used several times, the last one will be used.

              Added in 7.62.0.

       -D, --dump-header <filename>
              (HTTP  FTP) Write the received protocol headers to the specified
              file.

              This option is handy to use when you want to store  the  headers
              that  an  HTTP site sends to you. Cookies from the headers could
              then be read in a  second  curl  invocation  by  using  the  -b,
              --cookie  option! The -c, --cookie-jar option is a better way to
              store cookies.

              If no headers are received, the use of this option  will  create
              an empty file.

              When  used  in FTP, the FTP server response lines are considered
              being "headers" and thus are saved there.

              If this option is used several times, the last one will be used.

              See also -o, --output.

       --egd-file <file>
              (TLS)  Specify  the  path  name  to the Entropy Gathering Daemon
              socket. The socket is used to seed the  random  engine  for  SSL
              connections.

              See also --random-file.

       --engine <name>
              (TLS)  Select the OpenSSL crypto engine to use for cipher opera-
              tions. Use --engine list to print a list of build-time supported
              engines.  Note  that  not  all  (or  none) of the engines may be
              available at run-time.

       --etag-compare <file>
              (HTTP) This option makes a conditional HTTP request for the spe-
              cific ETag read from the given file by sending a custom If-None-
              Match header using the extracted ETag.

              For correct results, make sure that specified file contains only
              a single line with a desired ETag. An empty file is parsed as an
              empty ETag.

              Use the option  --etag-save  to  first  save  the  ETag  from  a
              response,  and  then  use this option to compare using the saved
              ETag in a subsequent request.

              COMPARISON: There are 2 types of comparison or ETags:  Weak  and
              Strong.  This option expects, and uses a strong comparison.

              Added in 7.68.0.

       --etag-save <file>
              (HTTP)  This  option  saves  an HTTP ETag to the specified file.
              Etag is usually part of headers  returned  by  a  request.  When
              server  sends  an  ETag, it must be enveloped by a double quote.
              This option extracts the ETag  without  the  double  quotes  and
              saves it into the <file>.

              A  server  can  send a weak ETag which is prefixed by "W/". This
              identifier is not considered, and  only  relevant  ETag  between
              quotation marks is parsed.

              It  an ETag wasn't sent by the server or it cannot be parsed, an
              empty file is created.

              Added in 7.68.0.

       --expect100-timeout <seconds>
              (HTTP) Maximum time in seconds that you allow curl to wait for a
              100-continue  response  when curl emits an Expects: 100-continue
              header in its request. By default curl  will  wait  one  second.
              This  option accepts decimal values! When curl stops waiting, it
              will continue as if the response has been received.

              See also --connect-timeout. Added in 7.47.0.

       --fail-early
              Fail and exit on the first detected transfer error.

              When curl is used to do multiple transfers on the command  line,
              it  will  attempt  to  operate on each given URL, one by one. By
              default, it will ignore errors if there are more URLs given  and
              the  last  URL's  success  will  determine  the  error code curl
              returns. So early failures will be "hidden" by  subsequent  suc-
              cessful transfers.

              Using  this  option,  curl  will  instead return an error on the
              first transfer that fails, independent of  the  amount  of  URLs
              that  are given on the command line. This way, no transfer fail-
              ures go undetected by scripts and similar.

              This option is global and does not need to be specified for each
              use of -:, --next.

              This option does not imply -f, --fail, which causes transfers to
              fail due to the server's HTTP status code. You can  combine  the
              two options, however note -f, --fail is not global and is there-
              fore contained by -:, --next.

              Added in 7.52.0.

       --fail-with-body
              (HTTP) Return an error on server errors where the HTTP  response
              code  is  400  or  greater). In normal cases when an HTTP server
              fails to deliver a document, it returns an HTML document stating
              so  (which  often  also  describes why and more). This flag will
              still allow curl to output and save that  content  but  also  to
              return error 22.

              This  is  an  alternative  option to -f, --fail which makes curl
              fail for the same circumstances but without saving the  content.

              See also -f, --fail. Added in 7.76.0.

       -f, --fail
              (HTTP)  Fail  silently (no output at all) on server errors. This
              is mostly done to enable scripts etc to better deal with  failed
              attempts. In normal cases when an HTTP server fails to deliver a
              document, it returns an HTML document stating  so  (which  often
              also  describes  why and more). This flag will prevent curl from
              outputting that and return error 22.

              This method is not fail-safe and there are occasions where  non-
              successful  response  codes  will  slip through, especially when
              authentication is involved (response codes 401 and 407).

              See also --fail-with-body.

       --false-start
              (TLS) Tells curl to use false start during  the  TLS  handshake.
              False  start  is  a  mode  where a TLS client will start sending
              application data before verifying the server's Finished message,
              thus saving a round trip when performing a full handshake.

              This  is currently only implemented in the NSS and Secure Trans-
              port (on iOS 7.0 or later, or OS X 10.9 or later) backends.

              Added in 7.42.0.

       --form-string <name=string>
              (HTTP SMTP IMAP) Similar to -F, --form  except  that  the  value
              string  for  the  named parameter is used literally. Leading '@'
              and '<' characters, and the ';type=' string in the value have no
              special meaning. Use this in preference to -F, --form if there's
              any possibility that the string value may  accidentally  trigger
              the '@' or '<' features of -F, --form.

              See also -F, --form.

       -F, --form <name=content>
              (HTTP  SMTP  IMAP) For HTTP protocol family, this lets curl emu-
              late a filled-in form in which a user  has  pressed  the  submit
              button.  This  causes  curl  to POST data using the Content-Type
              multipart/form-data according to RFC 2388.

              For SMTP and IMAP protocols, this is the mean to compose a  mul-
              tipart mail message to transmit.

              This  enables  uploading of binary files etc. To force the 'con-
              tent' part to be a file, prefix the file name with an @ sign. To
              just get the content part from a file, prefix the file name with
              the symbol <. The difference between @ and  <  is  then  that  @
              makes  a  file  get attached in the post as a file upload, while
              the < makes a text field and just get the contents for that text
              field from a file.

              Tell  curl to read content from stdin instead of a file by using
              - as filename. This goes for both @ and < constructs. When stdin
              is  used,  the  contents  is buffered in memory first by curl to
              determine its size and allow  a  possible  resend.   Defining  a
              part's  data from a named non-regular file (such as a named pipe
              or similar) is unfortunately not subject to buffering  and  will
              be effectively read at transmission time; since the full size is
              unknown before the transfer starts, such data is sent as  chunks
              by HTTP and rejected by IMAP.

              Example: send an image to an HTTP server, where 'profile' is the
              name of the form-field to which the file  portrait.jpg  will  be
              the input:

               curl -F profile=@portrait.jpg https://example.com/upload.cgi

              Example:  send your name and shoe size in two text fields to the
              server:

               curl -F name=John -F shoesize=11 https://example.com/

              Example: send your essay in a text field to the server. Send  it
              as  a plain text field, but get the contents for it from a local
              file:

               curl -F "story=<hugefile.txt" https://example.com/

              You can also  tell  curl  what  Content-Type  to  use  by  using
              'type=', in a manner similar to:

               curl -F "web=@index.html;type=text/html" example.com

              or

               curl -F "name=daniel;type=text/foo" example.com

              You  can  also explicitly change the name field of a file upload
              part by setting filename=, like this:

               curl -F "file=@localfile;filename=nameinpost" example.com

              If filename/path contains ',' or ';', it must be quoted by  dou-
              ble-quotes like:

               curl   -F  "file=@\"localfile\";filename=\"nameinpost\""  exam-
              ple.com

              or

               curl -F 'file=@"localfile";filename="nameinpost"' example.com

              Note that if a filename/path is  quoted  by  double-quotes,  any
              double-quote or backslash within the filename must be escaped by
              backslash.

              Quoting must also be applied to non-file  data  if  it  contains
              semicolons, leading/trailing spaces or leading double quotes:

               curl  -F  'colors="red;  green;  blue";type=text/x-myapp' exam-
              ple.com

              You can add custom headers to the  field  by  setting  headers=,
              like

                curl -F "submit=OK;headers=\"X-submit-type: OK\"" example.com

              or

                curl -F "submit=OK;headers=@headerfile" example.com

              The  headers=  keyword may appear more that once and above notes
              about quoting apply. When headers are read from  a  file,  Empty
              lines and lines starting with '#' are comments and ignored; each
              header can be folded by splitting between two words and starting
              the  continuation  line  with a space; embedded carriage-returns
              and trailing spaces are stripped.   Here  is  an  example  of  a
              header file contents:

                # This file contain two headers.
                X-header-1: this is a header

                # The following header is folded.
                X-header-2: this is
                 another header


              To  support  sending  multipart  mail  messages,  the  syntax is
              extended as follows:
              - name can be omitted: the equal sign is the first character  of
              the argument,
              -  if  data  starts with '(', this signals to start a new multi-
              part: it can be followed by a content type specification.
              - a multipart can be terminated with a '=)' argument.

              Example: the following command sends an SMTP  mime  e-mail  con-
              sisting in an inline part in two alternative formats: plain text
              and HTML. It attaches a text file:

               curl -F '=(;type=multipart/alternative' \
                       -F '=plain text message' \
                       -F '= <body>HTML message</body>;type=text/html' \
                    -F '=)' -F '=@textfile.txt' ...  smtp://example.com

              Data can be  encoded  for  transfer  using  encoder=.  Available
              encodings  are  binary and 8bit that do nothing else than adding
              the corresponding Content-Transfer-Encoding  header,  7bit  that
              only  rejects  8-bit  characters  with a transfer error, quoted-
              printable and base64 that encodes data according to  the  corre-
              sponding schemes, limiting lines length to 76 characters.

              Example:  send  multipart mail with a quoted-printable text mes-
              sage and a base64 attached file:

               curl -F '=text message;encoder=quoted-printable' \
                    -F '=@localfile;encoder=base64' ... smtp://example.com

              See further examples and details in the MANUAL.

              This option can be used multiple times.

              This  option  overrides  -d,  --data  and  -I,  --head  and  -T,
              --upload-file.

       --ftp-account <data>
              (FTP) When an FTP server asks for "account data" after user name
              and password has been provided, this data is sent off using  the
              ACCT command.

              If this option is used several times, the last one will be used.

              Added in 7.13.0.

       --ftp-alternative-to-user <command>
              (FTP) If authenticating with the USER and PASS  commands  fails,
              send  this  command.   When  connecting  to  Tumbleweed's Secure
              Transport server over FTPS using  a  client  certificate,  using
              "SITE  AUTH"  will tell the server to retrieve the username from
              the certificate.

              Added in 7.15.5.

       --ftp-create-dirs
              (FTP SFTP) When an FTP or SFTP URL/operation uses  a  path  that
              doesn't  currently exist on the server, the standard behavior of
              curl is to fail. Using this option, curl will instead attempt to
              create missing directories.

              See also --create-dirs.

       --ftp-method <method>
              (FTP)  Control what method curl should use to reach a file on an
              FTP(S) server. The method argument should be one of the  follow-
              ing alternatives:

              multicwd
                     curl  does  a  single CWD operation for each path part in
                     the given URL. For deep hierarchies this means very  many
                     commands.  This  is  how RFC 1738 says it should be done.
                     This is the default but the slowest behavior.

              nocwd  curl does no CWD at all. curl will do  SIZE,  RETR,  STOR
                     etc and give a full path to the server for all these com-
                     mands. This is the fastest behavior.

              singlecwd
                     curl does one CWD with the full target directory and then
                     operates  on  the  file  "normally" (like in the multicwd
                     case). This is somewhat  more  standards  compliant  than
                     'nocwd' but without the full penalty of 'multicwd'.

       Added in 7.15.1.

       --ftp-pasv
              (FTP)  Use  passive mode for the data connection. Passive is the
              internal default behavior, but using this option can be used  to
              override a previous -P, --ftp-port option.

              If  this  option  is  used  several times, only the first one is
              used. Undoing an enforced passive really isn't  doable  but  you
              must then instead enforce the correct -P, --ftp-port again.

              Passive mode means that curl will try the EPSV command first and
              then PASV, unless --disable-epsv is used.

              See also --disable-epsv. Added in 7.11.0.

       -P, --ftp-port <address>
              (FTP) Reverses the default initiator/listener  roles  when  con-
              necting  with  FTP. This option makes curl use active mode. curl
              then tells the server to connect back to the client's  specified
              address and port, while passive mode asks the server to setup an
              IP address and port for it to connect to.  <address>  should  be
              one of:

              interface
                     e.g.  "eth0"  to specify which interface's IP address you
                     want to use (Unix only)

              IP address
                     e.g. "192.168.10.1" to specify the exact IP address

              host name
                     e.g. "my.host.domain" to specify the machine

              -      make curl pick the same IP address that is  already  used
                     for the control connection

       If  this  option is used several times, the last one will be used. Dis-
       able the use of PORT with --ftp-pasv. Disable the attempt  to  use  the
       EPRT  command  instead  of PORT by using --disable-eprt. EPRT is really
       PORT++.

       Since 7.19.5, you can append  ":[start]-[end]"  to  the  right  of  the
       address,  to tell curl what TCP port range to use. That means you spec-
       ify a port range, from a lower to a  higher  number.  A  single  number
       works  as well, but do note that it increases the risk of failure since
       the port may not be available.

       See also --ftp-pasv and --disable-eprt.

       --ftp-pret
              (FTP) Tell curl to send a PRET command before PASV  (and  EPSV).
              Certain  FTP  servers,  mainly drftpd, require this non-standard
              command for directory listings as well as up  and  downloads  in
              PASV mode.

              Added in 7.20.0.

       --ftp-skip-pasv-ip
              (FTP) Tell curl to not use the IP address the server suggests in
              its response to curl's PASV command when curl connects the  data
              connection.  Instead  curl  will  re-use  the same IP address it
              already uses for the control connection.

              Since curl 7.74.0 this option is enabled by default.

              This option has no effect if PORT, EPRT or EPSV is used  instead
              of PASV.

              See also --ftp-pasv. Added in 7.14.2.

       --ftp-ssl-ccc-mode <active/passive>
              (FTP)  Sets the CCC mode. The passive mode will not initiate the
              shutdown, but instead wait for the server to do it, and will not
              reply to the shutdown from the server. The active mode initiates
              the shutdown and waits for a reply from the server.

              See also --ftp-ssl-ccc. Added in 7.16.2.

       --ftp-ssl-ccc
              (FTP) Use CCC (Clear Command Channel)  Shuts  down  the  SSL/TLS
              layer after authenticating. The rest of the control channel com-
              munication will be unencrypted. This allows NAT routers to  fol-
              low the FTP transaction. The default mode is passive.

              See also --ssl and --ftp-ssl-ccc-mode. Added in 7.16.1.

       --ftp-ssl-control
              (FTP)  Require  SSL/TLS  for  the FTP login, clear for transfer.
              Allows secure authentication, but non-encrypted  data  transfers
              for  efficiency.   Fails the transfer if the server doesn't sup-
              port SSL/TLS.

              Added in 7.16.0.

       -G, --get
              When used, this option will make all  data  specified  with  -d,
              --data,  --data-binary or --data-urlencode to be used in an HTTP
              GET request instead of the POST request that otherwise would  be
              used. The data will be appended to the URL with a '?' separator.

              If used in combination with  -I,  --head,  the  POST  data  will
              instead be appended to the URL with a HEAD request.

              If  this  option  is  used  several times, only the first one is
              used. This is because undoing a GET doesn't make sense, but  you
              should then instead enforce the alternative method you prefer.

       -g, --globoff
              This option switches off the "URL globbing parser". When you set
              this option, you can specify URLs that contain the letters  {}[]
              without  having them being interpreted by curl itself. Note that
              these letters are not normal legal URL contents but they  should
              be encoded according to the URI standard.

       --happy-eyeballs-timeout-ms <milliseconds>
              Happy  eyeballs is an algorithm that attempts to connect to both
              IPv4 and IPv6 addresses for dual-stack  hosts,  preferring  IPv6
              first for the number of milliseconds. If the IPv6 address cannot
              be connected to within that time then a  connection  attempt  is
              made to the IPv4 address in parallel. The first connection to be
              established is the one that is used.

              The range of suggested useful values is limited. Happy  Eyeballs
              RFC  6555  says  "It  is RECOMMENDED that connection attempts be
              paced 150-250 ms apart to balance human factors against  network
              load."  libcurl currently defaults to 200 ms. Firefox and Chrome
              currently default to 300 ms.

              If this option is used several times, the last one will be used.

              Added in 7.59.0.

       --haproxy-protocol
              (HTTP)  Send a HAProxy PROXY protocol v1 header at the beginning
              of the connection. This is  used  by  some  load  balancers  and
              reverse  proxies  to  indicate  the client's true IP address and
              port.

              This option is primarily useful when sending test requests to  a
              service that expects this header.

              Added in 7.60.0.

       -I, --head
              (HTTP FTP FILE) Fetch the headers only! HTTP-servers feature the
              command HEAD which this uses to get nothing but the header of  a
              document.  When  used  on an FTP or FILE file, curl displays the
              file size and last modification time only.

       -H, --header <header/@file>
              (HTTP) Extra header to include in the request when sending  HTTP
              to  a  server. You may specify any number of extra headers. Note
              that if you should add a custom header that has the same name as
              one  of  the  internal  ones curl would use, your externally set
              header will be used instead of the internal one. This allows you
              to  make  even  trickier  stuff than curl would normally do. You
              should not replace internally set headers without  knowing  per-
              fectly well what you're doing. Remove an internal header by giv-
              ing a replacement without content  on  the  right  side  of  the
              colon, as in: -H "Host:". If you send the custom header with no-
              value then its header must be terminated with a semicolon,  such
              as -H "X-Custom-Header;" to send "X-Custom-Header:".

              curl  will  make  sure  that each header you add/replace is sent
              with the proper end-of-line marker, you should thus not add that
              as a part of the header content: do not add newlines or carriage
              returns, they will only mess things up for you.

              This option can take an argument in @filename style, which  then
              adds  a  header  for  each line in the input file. Using @- will
              make curl read the header file from stdin. Added in 7.55.0.

              You need --proxy-header to send custom headers  intended  for  a
              HTTP proxy. Added in 7.37.0.

              Passing  on  a  "Transfer-Encoding: chunked" header when doing a
              HTTP request with a request body, will make curl send  the  data
              using chunked encoding.

              Example:

               curl -H "X-First-Name: Joe" http://example.com/

              WARNING:  headers  set  with  this  option  will  be  set in all
              requests - even after redirects are  followed,  like  when  told
              with  -L,  --location. This can lead to the header being sent to
              other hosts than the original host, so sensitive headers  should
              be used with caution combined with following redirects.

              This  option  can  be  used multiple times to add/replace/remove
              multiple headers.

              See also -A, --user-agent and -e, --referer.

       -h, --help <category>
              Usage help. This lists all commands of the  <category>.   If  no
              arg  was  provided, curl will display the most important command
              line arguments.  If the argument "all" was provided,  curl  will
              display  all  options available.  If the argument "category" was
              provided, curl will display all categories and their meanings.

       --hostpubmd5 <md5>
              (SFTP SCP) Pass a string containing 32 hexadecimal  digits.  The
              string  should  be the 128 bit MD5 checksum of the remote host's
              public key, curl will refuse the connection with the host unless
              the md5sums match.

              Added in 7.17.1.

       --hsts <file name>
              (HTTPS) WARNING: this option is experimental. Do not use in pro-
              duction.

              This option enables HSTS for the  transfer.  If  the  file  name
              points  to an existing HSTS cache file, that will be used. After
              a completed transfer, the cache will be saved to the  file  name
              again if it has been modified.

              Specify a "" file name (zero length) to avoid loading/saving and
              make curl just handle HSTS in memory.

              If this option is used several times, curl  will  load  contents
              from all the files but the last one will be used for saving.

              Added in 7.74.0.

       --http0.9
              (HTTP) Tells curl to be fine with HTTP version 0.9 response.

              HTTP/0.9  is  a completely headerless response and therefore you
              can also connect with this to non-HTTP servers and still  get  a
              response  since  curl  will  simply transparently downgrade - if
              allowed.

              Since curl 7.66.0, HTTP/0.9 is disabled by default.

       -0, --http1.0
              (HTTP) Tells curl to use HTTP version 1.0 instead of  using  its
              internally preferred HTTP version.

              This option overrides --http1.1 and --http2.

       --http1.1
              (HTTP) Tells curl to use HTTP version 1.1.

              This  option  overrides  -0,  --http1.0  and  --http2.  Added in
              7.33.0.

       --http2-prior-knowledge
              (HTTP) Tells curl to  issue  its  non-TLS  HTTP  requests  using
              HTTP/2  without  HTTP/1.1  Upgrade.  It requires prior knowledge
              that the server supports HTTP/2 straight  away.  HTTPS  requests
              will  still  do HTTP/2 the standard way with negotiated protocol
              version in the TLS handshake.

              --http2-prior-knowledge requires that the underlying libcurl was
              built to support HTTP/2. This option overrides --http1.1 and -0,
              --http1.0 and --http2. Added in 7.49.0.

       --http2
              (HTTP) Tells curl to use HTTP version 2.

              See also --http1.1 and --http3. --http2 requires that the under-
              lying libcurl was built to support HTTP/2. This option overrides
              --http1.1 and -0, --http1.0 and  --http2-prior-knowledge.  Added
              in 7.33.0.

       --http3
              (HTTP)  WARNING: this option is experimental. Do not use in pro-
              duction.

              Tells curl to use HTTP version 3 directly to the host  and  port
              number used in the URL. A normal HTTP/3 transaction will be done
              to a host and then get redirected via Alt-SVc, but  this  option
              allows  a  user to circumvent that when you know that the target
              speaks HTTP/3 on the given host and port.

              This option will make curl fail if a QUIC connection  cannot  be
              established,  it cannot fall back to a lower HTTP version on its
              own.

              See also --http1.1 and --http2. --http3 requires that the under-
              lying libcurl was built to support HTTP/3. This option overrides
              --http1.1 and -0, --http1.0 and --http2 and --http2-prior-knowl-
              edge. Added in 7.66.0.

       --ignore-content-length
              (FTP  HTTP)  For HTTP, Ignore the Content-Length header. This is
              particularly useful for servers running Apache 1.x,  which  will
              report  incorrect  Content-Length  for files larger than 2 giga-
              bytes.

              For FTP (since 7.46.0), skip the RETR command to figure out  the
              size before downloading a file.

       -i, --include
              Include  the  HTTP  response  headers  in  the  output. The HTTP
              response headers can include things like server  name,  cookies,
              date of the document, HTTP version and more...

              To  view the request headers, consider the -v, --verbose option.

              See also -v, --verbose.

       -k, --insecure
              (TLS) By default, every SSL connection curl makes is verified to
              be  secure.  This option allows curl to proceed and operate even
              for server connections otherwise considered insecure.

              The server connection is verified by making  sure  the  server's
              certificate  contains  the  right name and verifies successfully
              using the cert store.

              See this online resource for further details:
               https://curl.se/docs/sslcerts.html

              See also --proxy-insecure and --cacert.

       --interface <name>

              Perform an operation using a specified interface. You can  enter
              interface  name,  IP address or host name. An example could look
              like:

               curl --interface eth0:1 https://www.example.com/

              If this option is used several times, the last one will be used.

              On  Linux  it can be used to specify a VRF, but the binary needs
              to either have CAP_NET_RAW or to be run as root.  More  informa-
              tion   about  Linux  VRF:  https://www.kernel.org/doc/Documenta-
              tion/networking/vrf.txt

              See also --dns-interface.

       -4, --ipv4
              This option tells curl to resolve names to IPv4 addresses  only,
              and not for example try IPv6.

              See  also  --http1.1  and  --http2.  This  option  overrides -6,
              --ipv6.

       -6, --ipv6
              This option tells curl to resolve names to IPv6 addresses  only,
              and not for example try IPv4.

              See  also  --http1.1  and  --http2.  This  option  overrides -4,
              --ipv4.

       -j, --junk-session-cookies
              (HTTP) When curl is told to read cookies from a given file, this
              option  will  make  it  discard all "session cookies". This will
              basically have the same effect as if a new session  is  started.
              Typical  browsers  always  discard  session cookies when they're
              closed down.

              See also -b, --cookie and -c, --cookie-jar.

       --keepalive-time <seconds>
              This option sets the time a  connection  needs  to  remain  idle
              before  sending keepalive probes and the time between individual
              keepalive probes. It is currently effective on operating systems
              offering  the  TCP_KEEPIDLE  and  TCP_KEEPINTVL  socket  options
              (meaning Linux, recent AIX, HP-UX and more). This option has  no
              effect if --no-keepalive is used.

              If this option is used several times, the last one will be used.
              If unspecified, the option defaults to 60 seconds.

              Added in 7.18.0.

       --key-type <type>
              (TLS) Private key file type. Specify which type your --key  pro-
              vided  private  key  is. DER, PEM, and ENG are supported. If not
              specified, PEM is assumed.

              If this option is used several times, the last one will be used.

       --key <key>
              (TLS SSH) Private key file name. Allows you to provide your pri-
              vate key in this separate file. For SSH, if not specified,  curl
              tries   the  following  candidates  in  order:  '~/.ssh/id_rsa',
              '~/.ssh/id_dsa', './id_rsa', './id_dsa'.

              If curl is built against OpenSSL library, and the engine  pkcs11
              is available, then a PKCS#11 URI (RFC 7512) can be used to spec-
              ify a private key located in a PKCS#11 device. A  string  begin-
              ning  with  "pkcs11:" will be interpreted as a PKCS#11 URI. If a
              PKCS#11 URI is provided, then the --engine option will be set as
              "pkcs11"  if none was provided and the --key-type option will be
              set as "ENG" if none was provided.

              If this option is used several times, the last one will be used.

       --krb <level>
              (FTP)  Enable Kerberos authentication and use. The level must be
              entered and should be one of 'clear', 'safe', 'confidential', or
              'private'.  Should  you  use  a  level that is not one of these,
              'private' will instead be used.

              If this option is used several times, the last one will be used.

              --krb  requires that the underlying libcurl was built to support
              Kerberos.

       --libcurl <file>
              Append this option to any ordinary curl command  line,  and  you
              will  get a libcurl-using C source code written to the file that
              does the equivalent of what your command-line operation does!

              If this option is used several times, the last given  file  name
              will be used.

              Added in 7.16.1.

       --limit-rate <speed>
              Specify  the  maximum  transfer  rate you want curl to use - for
              both downloads and uploads. This feature is useful if you have a
              limited pipe and you'd like your transfer not to use your entire
              bandwidth. To make it slower than it otherwise would be.

              The given speed is measured in bytes/second, unless a suffix  is
              appended.   Appending  'k' or 'K' will count the number as kilo-
              bytes, 'm' or 'M' makes it megabytes, while 'g' or 'G' makes  it
              gigabytes. Examples: 200K, 3m and 1G.

              If  you  also use the -Y, --speed-limit option, that option will
              take precedence and might cripple the rate-limiting slightly, to
              help keeping the speed-limit logic working.

              If this option is used several times, the last one will be used.

       -l, --list-only
              (FTP POP3) (FTP) When listing  an  FTP  directory,  this  switch
              forces  a  name-only view. This is especially useful if the user
              wants to machine-parse the contents of an  FTP  directory  since
              the normal directory view doesn't use a standard look or format.
              When used like this, the option causes a NLST command to be sent
              to the server instead of LIST.

              Note:  Some  FTP  servers  list  only files in their response to
              NLST; they do not include sub-directories and symbolic links.

              (POP3) When retrieving a specific email from POP3,  this  switch
              forces  a  LIST command to be performed instead of RETR. This is
              particularly useful if the user wants to see if a specific  mes-
              sage id exists on the server and what size it is.

              Note:  When combined with -X, --request, this option can be used
              to send an UIDL command instead, so the user may use the email's
              unique  identifier  rather  than  it's  message  id  to make the
              request.

              Added in 4.0.

       --local-port <num/range>
              Set a preferred single number or range (FROM-TO) of  local  port
              numbers to use for the connection(s).  Note that port numbers by
              nature are a scarce resource that will be busy at times so  set-
              ting  this range to something too narrow might cause unnecessary
              connection setup failures.

              Added in 7.15.2.

       --location-trusted
              (HTTP) Like -L, --location, but will allow sending  the  name  +
              password to all hosts that the site may redirect to. This may or
              may not introduce a security breach if the site redirects you to
              a  site  to which you'll send your authentication info (which is
              plaintext in the case of HTTP Basic authentication).

              See also -u, --user.

       -L, --location
              (HTTP) If the server reports that the requested page  has  moved
              to a different location (indicated with a Location: header and a
              3XX response code), this option will make curl redo the  request
              on  the  new  place.  If used together with -i, --include or -I,
              --head, headers from all requested pages  will  be  shown.  When
              authentication  is  used, curl only sends its credentials to the
              initial host. If a redirect takes curl to a different  host,  it
              won't  be  able to intercept the user+password. See also --loca-
              tion-trusted on how to change this. You can limit the amount  of
              redirects to follow by using the --max-redirs option.

              When  curl  follows  a redirect and if the request is a POST, it
              will do the following request with a GET if  the  HTTP  response
              was  301,  302,  or  303. If the response code was any other 3x
              code, curl will re-send the following  request  using  the  same
              unmodified method.

              You can tell curl to not change POST requests to GET after a 30x
              response by using the dedicated  options  for  that:  --post301,
              --post302 and --post303.

              The  method  set  with  -X,  --request overrides the method curl
              would otherwise select to use.

       --login-options <options>
              (IMAP POP3 SMTP) Specify the login options to use during  server
              authentication.

              You  can  use  the  login  options  to specify protocol specific
              options that may be used during authentication. At present  only
              IMAP,  POP3 and SMTP support login options. For more information
              about the login options please see RFC 2384, RFC 5092  and  IETF
              draft draft-earhart-url-smtp-00.txt

              If this option is used several times, the last one will be used.

              Added in 7.34.0.

       --mail-auth <address>
              (SMTP) Specify a single address. This will be  used  to  specify
              the  authentication  address  (identity)  of a submitted message
              that is being relayed to another server.

              See also --mail-rcpt and --mail-from. Added in 7.25.0.

       --mail-from <address>
              (SMTP) Specify a single address that the given mail  should  get
              sent from.

              See also --mail-rcpt and --mail-auth. Added in 7.20.0.

       --mail-rcpt-allowfails
              (SMTP) When sending data to multiple recipients, by default curl
              will abort SMTP conversation if at least one of  the  recipients
              causes RCPT TO command to return an error.

              The  default  behavior  can  be  changed by passing --mail-rcpt-
              allowfails command-line  option  which  will  make  curl  ignore
              errors and proceed with the remaining valid recipients.

              In  case when all recipients cause RCPT TO command to fail, curl
              will abort SMTP conversation and return the error received  from
              to the last RCPT TO command.  Added in 7.69.0.

       --mail-rcpt <address>
              (SMTP) Specify a single address, user name or mailing list name.
              Repeat this option several times to send to multiple recipients.

              When  performing a mail transfer, the recipient should specify a
              valid email address to send the mail to.

              When performing an  address  verification  (VRFY  command),  the
              recipient  should be specified as the user name or user name and
              domain (as per Section 3.5 of RFC5321). (Added in 7.34.0)

              When performing a mailing list expand (EXPN command), the recip-
              ient  should  be  specified using the mailing list name, such as
              "Friends" or "London-Office".  (Added in 7.34.0)

              Added in 7.20.0.

       -M, --manual
              Manual. Display the huge help text.

       --max-filesize <bytes>
              Specify the maximum size (in bytes) of a file  to  download.  If
              the  file requested is larger than this value, the transfer will
              not start and curl will return with exit code 63.

              A size modifier may be used. For example, Appending 'k'  or  'K'
              will  count  the  number  as  kilobytes,  'm'  or  'M'  makes it
              megabytes, while 'g' or 'G' makes it gigabytes. Examples:  200K,
              3m and 1G. (Added in 7.58.0)

              NOTE:  The  file size is not always known prior to download, and
              for such files this option has no effect even if the file trans-
              fer  ends  up  being larger than this given limit. This concerns
              both FTP and HTTP transfers.

              See also --limit-rate.

       --max-redirs <num>
              (HTTP) Set maximum  number  of  redirection-followings  allowed.
              When  -L,  --location is used, is used to prevent curl from fol-
              lowing redirections too much. By default, the limit is set to 50
              redirections. Set this option to -1 to make it unlimited.

              If this option is used several times, the last one will be used.

       -m, --max-time <seconds>
              Maximum time in seconds that you allow the  whole  operation  to
              take.   This is useful for preventing your batch jobs from hang-
              ing for hours due to slow networks or links going  down.   Since
              7.32.0, this option accepts decimal values, but the actual time-
              out will decrease in accuracy as the specified timeout increases
              in decimal precision.

              If this option is used several times, the last one will be used.

              See also --connect-timeout.

       --metalink
              This option can tell curl to parse and process a  given  URI  as
              Metalink  file  (both  version 3 and 4 (RFC 5854) are supported)
              and make use of the mirrors listed within for failover if  there
              are  errors (such as the file or server not being available). It
              will also verify the hash of the file after  the  download  com-
              pletes.  The Metalink file itself is downloaded and processed in
              memory and not stored in the local file system.

              Example to use a remote Metalink file:

               curl --metalink http://www.example.com/example.metalink

              To use a Metalink file in the local file system, use FILE proto-
              col (file://):

               curl --metalink file:///example.metalink

              Please  note  that if FILE protocol is disabled, there is no way
              to use a local Metalink file at the time of this  writing.  Also
              note  that  if  --metalink  and -i, --include are used together,
              --include will be ignored. This is because including headers  in
              the  response  will break Metalink parser and if the headers are
              included in the file described in Metalink file, hash check will
              fail.

              --metalink  requires  that  the  underlying libcurl was built to
              support metalink. Added in 7.27.0.

       --negotiate
              (HTTP) Enables Negotiate (SPNEGO) authentication.

              This option requires a library built with GSS-API or  SSPI  sup-
              port.  Use  -V,  --version  to  see  if  your curl supports GSS-
              API/SSPI or SPNEGO.

              When using this option, you must also provide a fake -u,  --user
              option  to  activate the authentication code properly. Sending a
              '-u :' is enough as the user name  and  password  from  the  -u,
              --user option aren't actually used.

              If  this  option  is  used  several times, only the first one is
              used.

              See also --basic, --ntlm, --anyauth and --proxy-negotiate.

       --netrc-file <filename>
              This option is similar to -n, --netrc, except that  you  provide
              the  path  (absolute  or  relative)  to the netrc file that curl
              should use.  You can only specify one netrc file per invocation.
              If  several --netrc-file options are provided, the last one will
              be used.

              It will abide by --netrc-optional if specified.

              This option overrides -n, --netrc. Added in 7.21.5.

       --netrc-optional
              Very similar to -n, --netrc, but this option  makes  the  .netrc
              usage optional and not mandatory as the -n, --netrc option does.

              See also --netrc-file. This option overrides -n, --netrc.

       -n, --netrc
              Makes curl scan the .netrc  (_netrc  on  Windows)  file  in  the
              user's home directory for login name and password. This is typi-
              cally used for FTP on Unix. If used with HTTP, curl will  enable
              user authentication. See netrc(5) ftp(1) for details on the file
              format. Curl will not complain if that  file  doesn't  have  the
              right permissions (it should not be either world- or group-read-
              able). The environment variable "HOME" is used to find the  home
              directory.

              A  quick  and  very  simple  example of how to setup a .netrc to
              allow curl to FTP to the machine host.domain.com with user  name
              'myself' and password 'secret' should look similar to:

              machine host.domain.com login myself password secret

       -:, --next
              Tells curl to use a separate operation for the following URL and
              associated  options.  This  allows  you  to  send  several   URL
              requests,  each  with  their  own specific options, for example,
              such as different user names or custom requests for each.

              -:, --next will reset all local options  and  only  global  ones
              will  have  their values survive over to the operation following
              the -:, --next instruction. Global options  include  -v,  --ver-
              bose, --trace, --trace-ascii and --fail-early.

              For  example,  you can do both a GET and a POST in a single com-
              mand line:

               curl www1.example.com --next -d postthis www2.example.com

              Added in 7.36.0.

       --no-alpn
              (HTTPS) Disable the ALPN  TLS  extension.  ALPN  is  enabled  by
              default  if  libcurl was built with an SSL library that supports
              ALPN. ALPN is used by a libcurl that supports HTTP/2 to  negoti-
              ate HTTP/2 support with the server during https sessions.

              See  also  --no-npn  and  --http2.  --no-alpn  requires that the
              underlying libcurl was built to support TLS. Added in 7.36.0.

       -N, --no-buffer
              Disables the buffering of the output stream. In normal work sit-
              uations,  curl  will  use a standard buffered output stream that
              will have the effect that it will output the data in chunks, not
              necessarily  exactly  when  the data arrives.  Using this option
              will disable that buffering.

              Note that this is the negated option name  documented.  You  can
              thus use --buffer to enforce the buffering.

       --no-keepalive
              Disables  the  use  of keepalive messages on the TCP connection.
              curl otherwise enables them by default.

              Note that this is the negated option name  documented.  You  can
              thus use --keepalive to enforce keepalive.

       --no-npn
              (HTTPS) Disable the NPN TLS extension. NPN is enabled by default
              if libcurl was built with an SSL library that supports NPN.  NPN
              is  used  by  a libcurl that supports HTTP/2 to negotiate HTTP/2
              support with the server during https sessions.

              See also --no-alpn  and  --http2.  --no-npn  requires  that  the
              underlying libcurl was built to support TLS. Added in 7.36.0.

       --no-progress-meter
              Option to switch off the progress meter output without muting or
              otherwise affecting warning and informational messages like  -s,
              --silent does.

              Note  that  this  is the negated option name documented. You can
              thus use --progress-meter to enable the progress meter again.

              See also -v, --verbose and -s, --silent. Added in 7.67.0.

       --no-sessionid
              (TLS) Disable curl's use of SSL session-ID caching.  By  default
              all  transfers are done using the cache. Note that while nothing
              should ever get hurt by attempting  to  reuse  SSL  session-IDs,
              there seem to be broken SSL implementations in the wild that may
              require you to disable this in order for you to succeed.

              Note that this is the negated option name  documented.  You  can
              thus use --sessionid to enforce session-ID caching.

              Added in 7.16.0.

       --noproxy <no-proxy-list>
              Comma-separated  list  of hosts which do not use a proxy, if one
              is specified.  The only wildcard is a single * character,  which
              matches all hosts, and effectively disables the proxy. Each name
              in this list is matched as either a domain  which  contains  the
              hostname,  or  the hostname itself. For example, local.com would
              match  local.com,  local.com:80,  and  www.local.com,  but   not
              www.notlocal.com.

              Since  7.53.0,  This  option overrides the environment variables
              that disable the proxy. If there's an environment variable  dis-
              abling a proxy, you can set noproxy list to "" to override it.

              Added in 7.19.4.

       --ntlm-wb
              (HTTP) Enables NTLM much in the style --ntlm does, but hand over
              the authentication to the separate binary  ntlmauth  application
              that is executed when needed.

              See also --ntlm and --proxy-ntlm.

       --ntlm (HTTP)  Enables  NTLM  authentication.  The  NTLM authentication
              method was designed by Microsoft and is used by IIS web servers.
              It  is a proprietary protocol, reverse-engineered by clever peo-
              ple and implemented in curl based on their efforts. This kind of
              behavior  should  not be endorsed, you should encourage everyone
              who uses NTLM to switch to a public and  documented  authentica-
              tion method instead, such as Digest.

              If  you  want to enable NTLM for your proxy authentication, then
              use --proxy-ntlm.

              If this option is used several times,  only  the  first  one  is
              used.

              See  also  --proxy-ntlm.  --ntlm  requires  that  the underlying
              libcurl was built to support TLS. This option overrides  --basic
              and --negotiate and --digest and --anyauth.

       --oauth2-bearer <token>
              (IMAP  POP3  SMTP  HTTP)  Specify the Bearer Token for OAUTH 2.0
              server authentication. The Bearer Token is used  in  conjunction
              with  the  user name which can be specified as part of the --url
              or -u, --user options.

              The Bearer Token and user name are formatted  according  to  RFC
              6750.

              If this option is used several times, the last one will be used.

       --output-dir <dir>

              This option specifies the directory in  which  files  should  be
              stored, when -O, --remote-name or -o, --output are used.

              The  given  output  directory  is  used  for all URLs and output
              options on the command line, up until the first -:, --next.

              If the specified target directory doesn't exist,  the  operation
              will fail unless --create-dirs is also used.

              If this option is used multiple times, the last specified direc-
              tory will be used.

              See also -O, --remote-name and -J,  --remote-header-name.  Added
              in 7.73.0.

       -o, --output <file>
              Write output to <file> instead of stdout. If you are using {} or
              [] to fetch multiple documents, you should quote the URL and you
              can  use  '#' followed by a number in the <file> specifier. That
              variable will be replaced with the current string  for  the  URL
              being fetched. Like in:

               curl "http://{one,two}.example.com" -o "file_#1.txt"

              or use several variables like:

               curl "http://{site,host}.host[1-5].com" -o "#1_#2"

              You  may use this option as many times as the number of URLs you
              have. For example, if you specify two URLs on the  same  command
              line, you can use it like this:

                curl -o aa example.com -o bb example.net

              and  the  order  of  the -o options and the URLs doesn't matter,
              just that the first -o is for the first URL and so  on,  so  the
              above command line can also be written as

                curl example.com example.net -o aa -o bb

              See  also  the --create-dirs option to create the local directo-
              ries dynamically. Specifying the output as '-' (a  single  dash)
              will force the output to be done to stdout.

              See  also -O, --remote-name, --remote-name-all and -J, --remote-
              header-name.

       --parallel-immediate
              When doing parallel transfers, this option  will  instruct  curl
              that it should rather prefer opening up more connections in par-
              allel at once rather than waiting to see if new transfers can be
              added as multiplexed streams on another connection.

              See also -Z, --parallel and --parallel-max. Added in 7.68.0.

       --parallel-max
              When  asked to do parallel transfers, using -Z, --parallel, this
              option controls the maximum amount of transfers to do simultane-
              ously.

              The default is 50.

              See also -Z, --parallel. Added in 7.66.0.

       -Z, --parallel
              Makes  curl perform its transfers in parallel as compared to the
              regular serial manner.

              Added in 7.66.0.

       --pass <phrase>
              (SSH TLS) Passphrase for the private key

              If this option is used several times, the last one will be used.

       --path-as-is
              Tell  curl  to  not handle sequences of /../ or /./ in the given
              URL path. Normally curl will squash or merge them  according  to
              standards but with this option set you tell it not to do that.

              Added in 7.42.0.

       --pinnedpubkey <hashes>
              (TLS)  Tells  curl  to  use  the  specified  public key file (or
              hashes) to verify the peer. This can be a path to a  file  which
              contains a single public key in PEM or DER format, or any number
              of base64 encoded sha256 hashes preceded by 'sha256//' and sepa-
              rated by ';'

              When  negotiating  a  TLS  or SSL connection, the server sends a
              certificate indicating its identity. A public key  is  extracted
              from  this certificate and if it does not exactly match the pub-
              lic key provided to this option, curl will abort the  connection
              before sending or receiving any data.

              PEM/DER support:
                7.39.0: OpenSSL, GnuTLS and GSKit
                7.43.0: NSS and wolfSSL
                7.47.0: mbedtls sha256 support:
                7.44.0: OpenSSL, GnuTLS, NSS and wolfSSL
                7.47.0: mbedtls Other SSL backends not supported.

              If this option is used several times, the last one will be used.

       --post301
              (HTTP) Tells curl to respect RFC 7231/6.4.2 and not convert POST
              requests into GET requests when following a 301 redirection. The
              non-RFC behavior is ubiquitous in web browsers, so curl does the
              conversion by default to maintain consistency. However, a server
              may require a POST to remain a POST after  such  a  redirection.
              This option is meaningful only when using -L, --location.

              See  also  --post302,  --post303  and  -L,  --location. Added in
              7.17.1.

       --post302
              (HTTP) Tells curl to respect RFC 7231/6.4.3 and not convert POST
              requests into GET requests when following a 302 redirection. The
              non-RFC behavior is ubiquitous in web browsers, so curl does the
              conversion by default to maintain consistency. However, a server
              may require a POST to remain a POST after  such  a  redirection.
              This option is meaningful only when using -L, --location.

              See  also  --post301,  --post303  and  -L,  --location. Added in
              7.19.1.

       --post303
              (HTTP) Tells curl to violate RFC 7231/6.4.4 and not convert POST
              requests  into  GET  requests when following 303 redirections. A
              server may require a POST to remain a POST after a 303 redirect-
              ion. This option is meaningful only when using -L, --location.

              See  also  --post302,  --post301  and  -L,  --location. Added in
              7.26.0.

       --preproxy [protocol://]host[:port]
              Use the specified SOCKS proxy before connecting to  an  HTTP  or
              HTTPS  -x,  --proxy.  In  such a case curl first connects to the
              SOCKS proxy and then connects (through SOCKS)  to  the  HTTP  or
              HTTPS proxy. Hence pre proxy.

              The pre proxy string should be specified with a protocol:// pre-
              fix to  specify  alternative  proxy  protocols.  Use  socks4://,
              socks4a://,  socks5://  or  socks5h://  to  request the specific
              SOCKS version to be used. No protocol specified will  make  curl
              default to SOCKS4.

              If  the  port number is not specified in the proxy string, it is
              assumed to be 1080.

              User and password that might be provided in the proxy string are
              URL  decoded by curl. This allows you to pass in special charac-
              ters such as @ by using %40 or pass in a colon with %3a.

              If this option is used several times, the last one will be used.

              Added in 7.52.0.

       -#, --progress-bar
              Make  curl  display  transfer  progress as a simple progress bar
              instead of the standard, more informational, meter.

              This progress bar draws a single line of '#'  characters  across
              the screen and shows a percentage if the transfer size is known.
              For transfers without a known size, there  will  be  space  ship
              (-=o=-)  that  moves back and forth but only while data is being
              transferred, with a set of flying hash sign symbols on top.

       --proto-default <protocol>
              Tells curl to use protocol for any URL missing a scheme name.

              Example:

               curl --proto-default https ftp.mozilla.org

              An unknown or unsupported  protocol  causes  error  CURLE_UNSUP-
              PORTED_PROTOCOL (1).

              This option does not change the default proxy protocol (http).

              Without  this  option curl would make a guess based on the host,
              see --url for details.

              Added in 7.45.0.

       --proto-redir <protocols>
              Tells curl to limit what protocols it may use on redirect.  Pro-
              tocols  denied by --proto are not overridden by this option. See
              --proto for how protocols are represented.

              Example, allow only HTTP and HTTPS on redirect:

               curl --proto-redir -all,http,https http://example.com

              By default curl will allow HTTP, HTTPS, FTP and FTPS on redirect
              (7.65.2).  Older versions of curl allowed all protocols on redi-
              rect except several disabled for security reasons: Since  7.19.4
              FILE  and  SCP  are  disabled, and since 7.40.0 SMB and SMBS are
              also disabled. Specifying all or +all enables all  protocols  on
              redirect, including those disabled for security.

              Added in 7.20.2.

       --proto <protocols>
              Tells  curl  to limit what protocols it may use in the transfer.
              Protocols are evaluated left to right, are comma separated,  and
              are  each  a protocol name or 'all', optionally prefixed by zero
              or more modifiers. Available modifiers are:

              +  Permit this protocol in addition to protocols already permit-
                 ted (this is the default if no modifier is used).

              -  Deny  this  protocol,  removing it from the list of protocols
                 already permitted.

              =  Permit only this protocol (ignoring the list already  permit-
                 ted),  though  subject  to  later  modification by subsequent
                 entries in the comma separated list.

              For example:

              --proto -ftps  uses the default protocols, but disables ftps

              --proto -all,https,+http
                             only enables http and https

              --proto =http,https
                             also only enables http and https

       Unknown protocols produce a warning. This allows scripts to safely rely
       on being able to disable potentially dangerous protocols, without rely-
       ing upon support for that protocol being built into curl  to  avoid  an
       error.

       This option can be used multiple times, in which case the effect is the
       same as concatenating the protocols into one instance of the option.

       See also --proto-redir and --proto-default. Added in 7.20.2.

       --proxy-anyauth
              Tells curl to pick a suitable authentication method when  commu-
              nicating  with  the  given HTTP proxy. This might cause an extra
              request/response round-trip.

              See also -x, --proxy, --proxy-basic and --proxy-digest. Added in
              7.13.2.

       --proxy-basic
              Tells  curl  to use HTTP Basic authentication when communicating
              with the given proxy. Use --basic for enabling HTTP Basic with a
              remote  host.  Basic  is  the default authentication method curl
              uses with proxies.

              See also -x, --proxy, --proxy-anyauth and --proxy-digest.

       --proxy-cacert <file>
              Same as --cacert but used in HTTPS proxy context.

              See also --proxy-capath, --cacert,  --capath  and  -x,  --proxy.
              Added in 7.52.0.

       --proxy-capath <dir>
              Same as --capath but used in HTTPS proxy context.

              See  also  --proxy-cacert,  -x,  --proxy  and --capath. Added in
              7.52.0.

       --proxy-cert-type <type>
              Same as --cert-type but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-cert <cert[:passwd]>
              Same as -E, --cert but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-ciphers <list>
              Same as --ciphers but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-crlfile <file>
              Same as --crlfile but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-digest
              Tells curl to use HTTP Digest authentication when  communicating
              with the given proxy. Use --digest for enabling HTTP Digest with
              a remote host.

              See also -x, --proxy, --proxy-anyauth and --proxy-basic.

       --proxy-header <header/@file>
              (HTTP) Extra header to include in the request when sending  HTTP
              to a proxy. You may specify any number of extra headers. This is
              the equivalent option to -H, --header but is for proxy  communi-
              cation  only  like  in CONNECT requests when you want a separate
              header sent to the proxy to what is sent to  the  actual  remote
              host.

              curl  will  make  sure  that each header you add/replace is sent
              with the proper end-of-line marker, you should thus not add that
              as a part of the header content: do not add newlines or carriage
              returns, they will only mess things up for you.

              Headers specified with this  option  will  not  be  included  in
              requests that curl knows will not be sent to a proxy.

              Starting  in  7.55.0, this option can take an argument in @file-
              name style, which then adds a header for each line in the  input
              file. Using @- will make curl read the header file from stdin.

              This  option  can  be  used multiple times to add/replace/remove
              multiple headers.

              Added in 7.37.0.

       --proxy-insecure
              Same as -k, --insecure but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-key-type <type>
              Same as --key-type but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-key <key>
              Same as --key but used in HTTPS proxy context.

       --proxy-negotiate
              Tells curl to use HTTP Negotiate  (SPNEGO)  authentication  when
              communicating with the given proxy. Use --negotiate for enabling
              HTTP Negotiate (SPNEGO) with a remote host.

              See also --proxy-anyauth and --proxy-basic. Added in 7.17.1.

       --proxy-ntlm
              Tells curl to use HTTP NTLM  authentication  when  communicating
              with the given proxy. Use --ntlm for enabling NTLM with a remote
              host.

              See also --proxy-negotiate and --proxy-anyauth.

       --proxy-pass <phrase>
              Same as --pass but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-pinnedpubkey <hashes>
              (TLS) Tells curl to  use  the  specified  public  key  file  (or
              hashes)  to verify the proxy. This can be a path to a file which
              contains a single public key in PEM or DER format, or any number
              of base64 encoded sha256 hashes preceded by 'sha256//' and sepa-
              rated by ';'

              When negotiating a TLS or SSL connection,  the  server  sends  a
              certificate  indicating  its identity. A public key is extracted
              from this certificate and if it does not exactly match the  pub-
              lic  key provided to this option, curl will abort the connection
              before sending or receiving any data.

              If this option is used several times, the last one will be used.

       --proxy-service-name <name>
              This  option  allows  you  to  change the service name for proxy
              negotiation.

              Added in 7.43.0.

       --proxy-ssl-allow-beast
              Same as --ssl-allow-beast but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-ssl-auto-client-cert
              Same as --ssl-auto-client-cert but used in HTTPS proxy  context.

              Added in 7.77.0.

       --proxy-tls13-ciphers <ciphersuite list>
              (TLS)  Specifies which cipher suites to use in the connection to
              your HTTPS proxy when it negotiates TLS 1.3. The list of ciphers
              suites  must  specify  valid  ciphers. Read up on TLS 1.3 cipher
              suite details on this URL:

               https://curl.se/docs/ssl-ciphers.html

              This option is currently used only when curl  is  built  to  use
              OpenSSL 1.1.1 or later. If you are using a different SSL backend
              you can try setting TLS 1.3 cipher suites by using the  --proxy-
              ciphers option.

              If this option is used several times, the last one will be used.

       --proxy-tlsauthtype <type>
              Same as --tlsauthtype but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-tlspassword <string>
              Same as --tlspassword but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-tlsuser <name>
              Same as --tlsuser but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-tlsv1
              Same as -1, --tlsv1 but used in HTTPS proxy context.

              Added in 7.52.0.

       -U, --proxy-user <user:password>
              Specify the user name and password to use for proxy  authentica-
              tion.

              If  you  use  a  Windows  SSPI-enabled curl binary and do either
              Negotiate or NTLM authentication  then  you  can  tell  curl  to
              select the user name and password from your environment by spec-
              ifying a single colon with this option: "-U :".

              On systems where it works, curl will hide the given option argu-
              ment  from  process listings. This is not enough to protect cre-
              dentials from possibly getting seen by other users on  the  same
              system  as  they will still be visible for a brief moment before
              cleared. Such sensitive data should be  retrieved  from  a  file
              instead  or  similar  and  never used in clear text in a command
              line.

              If this option is used several times, the last one will be used.

       -x, --proxy [protocol://]host[:port]
              Use the specified proxy.

              The  proxy string can be specified with a protocol:// prefix. No
              protocol specified or http:// will be treated as HTTP proxy. Use
              socks4://, socks4a://, socks5:// or socks5h:// to request a spe-
              cific SOCKS version to be used.  (The protocol support was added
              in curl 7.21.7)

              HTTPS  proxy  support  via https:// protocol prefix was added in
              7.52.0 for OpenSSL, GnuTLS and NSS.

              Unrecognized and unsupported  proxy  protocols  cause  an  error
              since  7.52.0.   Prior  versions may ignore the protocol and use
              http:// instead.

              If the port number is not specified in the proxy string,  it  is
              assumed to be 1080.

              This  option  overrides  existing environment variables that set
              the proxy to use. If there's an environment variable  setting  a
              proxy, you can set proxy to "" to override it.

              All operations that are performed over an HTTP proxy will trans-
              parently be converted to HTTP. It means  that  certain  protocol
              specific operations might not be available. This is not the case
              if you can tunnel through the proxy, as one with the -p, --prox-
              ytunnel option.

              User and password that might be provided in the proxy string are
              URL decoded by curl. This allows you to pass in special  charac-
              ters such as @ by using %40 or pass in a colon with %3a.

              The  proxy host can be specified the exact same way as the proxy
              environment variables, including the protocol  prefix  (http://)
              and the embedded user + password.

              If this option is used several times, the last one will be used.

       --proxy1.0 <host[:port]>
              Use the specified HTTP 1.0 proxy. If  the  port  number  is  not
              specified, it is assumed at port 1080.

              The  only  difference between this and the HTTP proxy option -x,
              --proxy, is that attempts to use CONNECT through the proxy  will
              specify an HTTP 1.0 protocol instead of the default HTTP 1.1.

       -p, --proxytunnel
              When  an  HTTP  proxy is used -x, --proxy, this option will make
              curl tunnel through the proxy. The tunnel approach is made  with
              the  HTTP  proxy  CONNECT  request  and  requires that the proxy
              allows direct connect to the remote port number  curl  wants  to
              tunnel through to.

              To  suppress  proxy CONNECT response headers when curl is set to
              output headers use --suppress-connect-headers.

              See also -x, --proxy.

       --pubkey <key>
              (SFTP SCP) Public key file name. Allows you to provide your pub-
              lic key in this separate file.

              If this option is used several times, the last one will be used.

              (As of 7.39.0, curl attempts to automatically extract the public
              key  from the private key file, so passing this option is gener-
              ally not required. Note that this public key extraction requires
              libcurl  to  be linked against a copy of libssh2 1.2.8 or higher
              that is itself linked against OpenSSL.)

       -Q, --quote
              (FTP SFTP) Send an arbitrary command to the remote FTP  or  SFTP
              server.  Quote commands are sent BEFORE the transfer takes place
              (just after the initial PWD command in an FTP  transfer,  to  be
              exact). To make commands take place after a successful transfer,
              prefix them with a dash '-'.  To make  commands  be  sent  after
              curl has changed the working directory, just before the transfer
              command(s), prefix the command with a '+'  (this  is  only  sup-
              ported for FTP). You may specify any number of commands.

              If  the  server  returns  failure  for  one of the commands, the
              entire operation will be aborted. You  must  send  syntactically
              correct  FTP  commands as RFC 959 defines to FTP servers, or one
              of the commands listed below to SFTP servers.

              Prefix the command with an asterisk (*) to  make  curl  continue
              even  if the command fails as by default curl will stop at first
              failure.

              This option can be used multiple times.

              SFTP is a binary protocol. Unlike for FTP, curl interprets  SFTP
              quote  commands  itself before sending them to the server.  File
              names may be quoted shell-style to embed spaces or special char-
              acters.   Following is the list of all supported SFTP quote com-
              mands:

              atime date file
                     The atime command sets the last access time of  the  file
                     named  by  the file operand. The <date expression> can be
                     all sorts of date strings, see  the  curl_getdate(3)  man
                     page for date expression details. (Added in 7.73.0)

              chgrp group file
                     The  chgrp command sets the group ID of the file named by
                     the file operand to the group ID specified by  the  group
                     operand. The group operand is a decimal integer group ID.

              chmod mode file
                     The chmod command modifies the  file  mode  bits  of  the
                     specified file. The mode operand is an octal integer mode
                     number.

              chown user file
                     The chown command sets the owner of the file named by the
                     file  operand  to the user ID specified by the user oper-
                     and. The user operand is a decimal integer user ID.

              ln source_file target_file
                     The ln and symlink commands create a symbolic link at the
                     target_file  location  pointing  to the source_file loca-
                     tion.

              mkdir directory_name
                     The mkdir command creates  the  directory  named  by  the
                     directory_name operand.

              mtime date file
                     The  mtime command sets the last modification time of the
                     file named by the file operand. The <date expression> can
                     be all sorts of date strings, see the curl_getdate(3) man
                     page for date expression details. (Added in 7.73.0)

              pwd    The pwd command returns the absolute pathname of the cur-
                     rent working directory.

              rename source target
                     The rename command renames the file or directory named by
                     the source operand to the destination path named  by  the
                     target operand.

              rm file
                     The rm command removes the file specified by the file op-
                     erand.

              rmdir directory
                     The rmdir command removes the directory  entry  specified
                     by the directory operand, provided it is empty.

              symlink source_file target_file
                     See ln.

       --random-file <file>
              Specify the path name to file containing what will be considered
              as random data. The data may be used to seed the  random  engine
              for SSL connections.  See also the --egd-file option.

       -r, --range <range>
              (HTTP FTP SFTP FILE) Retrieve a byte range (i.e. a partial docu-
              ment) from an HTTP/1.1, FTP or SFTP  server  or  a  local  FILE.
              Ranges can be specified in a number of ways.

              0-499     specifies the first 500 bytes

              500-999   specifies the second 500 bytes

              -500      specifies the last 500 bytes

              9500-     specifies the bytes from offset 9500 and forward

              0-0,-1    specifies the first and last byte only(*)(HTTP)

              100-199,500-599
                        specifies two separate 100-byte ranges(*) (HTTP)

              (*)  = NOTE that this will cause the server to reply with a mul-
              tipart response, which will be returned as-is by  curl!  Parsing
              or otherwise transforming this response is the responsibility of
              the caller.

              Only digit characters (0-9) are valid in the 'start' and  'stop'
              fields  of the 'start-stop' range syntax. If a non-digit charac-
              ter is given in the range, the server's response will be unspec-
              ified, depending on the server's configuration.

              You  should also be aware that many HTTP/1.1 servers do not have
              this feature enabled, so that when you attempt to get  a  range,
              you'll instead get the whole document.

              FTP  and  SFTP  range  downloads only support the simple 'start-
              stop' syntax (optionally with one of the numbers  omitted).  FTP
              use depends on the extended FTP command SIZE.

              If this option is used several times, the last one will be used.

       --raw  (HTTP) When used, it disables all internal HTTP decoding of con-
              tent  or  transfer  encodings  and  instead makes them passed on
              unaltered, raw.

              Added in 7.16.2.

       -e, --referer <URL>
              (HTTP) Sends the "Referrer Page" information to the HTTP server.
              This can also be set with the -H, --header flag of course.  When
              used with -L, --location you  can  append  ";auto"  to  the  -e,
              --referer  URL  to  make curl automatically set the previous URL
              when it follows a Location: header. The ";auto"  string  can  be
              used alone, even if you don't set an initial -e, --referer.

              If this option is used several times, the last one will be used.

              See also -A, --user-agent and -H, --header.

       -J, --remote-header-name
              (HTTP) This option tells the -O, --remote-name option to use the
              server-specified   Content-Disposition   filename   instead   of
              extracting a filename from the URL.

              If the server specifies a file name and a file  with  that  name
              already  exists  in the current working directory it will not be
              overwritten and an error will occur. If the server doesn't spec-
              ify a file name then this option has no effect.

              There's  no  attempt to decode %-sequences (yet) in the provided
              file name, so this option may provide you with rather unexpected
              file names.

              WARNING:  Exercise  judicious  use of this option, especially on
              Windows. A rogue server could send you the  name  of  a  DLL  or
              other  file  that could possibly be loaded automatically by Win-
              dows or some third party software.

       --remote-name-all
              This option changes the default action for all given URLs to  be
              dealt with as if -O, --remote-name were used for each one. So if
              you want to disable that for a specific URL after --remote-name-
              all has been used, you must use "-o -" or --no-remote-name.

              Added in 7.19.0.

       -O, --remote-name
              Write  output to a local file named like the remote file we get.
              (Only the file part of the remote file is used, the path is  cut
              off.)

              The  file will be saved in the current working directory. If you
              want the file saved in a  different  directory,  make  sure  you
              change  the  current working directory before invoking curl with
              this option.

              The remote file name to use for saving  is  extracted  from  the
              given  URL,  nothing  else,  and if it already exists it will be
              overwritten. If you want the server to be  able  to  choose  the
              file name refer to -J, --remote-header-name which can be used in
              addition to this option. If the server chooses a file  name  and
              that name already exists it will not be overwritten.

              There is no URL decoding done on the file name. If it has %20 or
              other URL encoded parts of the name, they will end up  as-is  as
              file name.

              You  may use this option as many times as the number of URLs you
              have.

       -R, --remote-time
              When used, this will make curl attempt to figure out  the  time-
              stamp  of  the  remote  file,  and if that is available make the
              local file get that same timestamp.

       --request-target
              (HTTP) Tells curl to use an alternative "target" (path)  instead
              of  using  the  path as provided in the URL. Particularly useful
              when wanting to issue HTTP requests  without  leading  slash  or
              other  data  that  doesn't  follow the regular URL pattern, like
              "OPTIONS *".

              Added in 7.55.0.

       -X, --request <command>
              (HTTP) Specifies a custom request method to use when communicat-
              ing  with the HTTP server.  The specified request method will be
              used instead of the method otherwise  used  (which  defaults  to
              GET).  Read  the HTTP 1.1 specification for details and explana-
              tions. Common additional HTTP requests include PUT  and  DELETE,
              but related technologies like WebDAV offers PROPFIND, COPY, MOVE
              and more.

              Normally you don't need this option. All  sorts  of  GET,  HEAD,
              POST and PUT requests are rather invoked by using dedicated com-
              mand line options.

              This option only changes  the  actual  word  used  in  the  HTTP
              request,  it does not alter the way curl behaves. So for example
              if you want to make a proper HEAD request, using  -X  HEAD  will
              not suffice. You need to use the -I, --head option.

              The  method  string  you set with -X, --request will be used for
              all requests, which if you for example use  -L,  --location  may
              cause  unintended  side-effects when curl doesn't change request
              method according to the HTTP 30x response codes - and similar.

              (FTP) Specifies a custom FTP command to use instead of LIST when
              doing file lists with FTP.

              (POP3) Specifies a custom POP3 command to use instead of LIST or
              RETR. (Added in 7.26.0)

              (IMAP) Specifies a custom IMAP command to use instead  of  LIST.
              (Added in 7.30.0)

              (SMTP) Specifies a custom SMTP command to use instead of HELP or
              VRFY. (Added in 7.34.0)

              If this option is used several times, the last one will be used.

       --resolve <[+]host:port:addr[,addr]...>
              Provide  a  custom  address  for  a specific host and port pair.
              Using this, you can make the curl requests(s)  use  a  specified
              address  and  prevent the otherwise normally resolved address to
              be used. Consider it a sort of /etc/hosts  alternative  provided
              on  the  command line. The port number should be the number used
              for the specific protocol the host will be used  for.  It  means
              you  need several entries if you want to provide address for the
              same host but different ports.

              By specifying '*' as host you can tell curl to resolve any  host
              and  specific  port  pair  to the specified address. Wildcard is
              resolved last so any --resolve with a  specific  host  and  port
              will be used first.

              The provided address set by this option will be used even if -4,
              --ipv4 or -6, --ipv6 is set to make curl use another IP version.

              By prefixing the host with a '+' you can make the entry time out
              after curl's default timeout (1 minute).  Note  that  this  will
              only  make  sense for long running parallel transfers with a lot
              of files. In such cases, if this option is used curl will try to
              resolve  the  host  as  it  normally  would once the timeout has
              expired.

              Support for providing the IP address within [brackets] was added
              in 7.57.0.

              Support  for providing multiple IP addresses per entry was added
              in 7.59.0.

              Support for resolving with wildcard was added in 7.64.0.

              Support for the '+' prefix was was added in 7.75.0.

              This option can be used many times to add  many  host  names  to
              resolve.

              Added in 7.21.3.

       --retry-all-errors
              Retry on any error. This option is used together with --retry.

              This  option  is the "sledgehammer" of retrying. Do not use this
              option by default (eg in curlrc), there may be unintended conse-
              quences  such as sending or receiving duplicate data. Do not use
              with redirected input or output. You'd be much better  off  han-
              dling  your  unique  problems  in  shell script. Please read the
              example below.

              Warning: For server compatibility curl attempts to retry  failed
              flaky  transfers  as close as possible to how they were started,
              but this is not possible with redirected input  or  output.  For
              example,  before  retrying  it removes output data from a failed
              partial transfer that was written to  an  output  file.  However
              this is not true of data redirected to a | pipe or > file, which
              are not reset. We strongly suggest don't parse or record  output
              via  redirect  in  combination  with  this option, since you may
              receive duplicate data.

              By default curl will not error on an  HTTP  response  code  that
              indicates  an  HTTP  error,  if the transfer was successful. For
              example, if a server replies 404 Not  Found  and  the  reply  is
              fully  received  then that is not an error. When --retry is used
              then curl will retry on some HTTP response codes  that  indicate
              transient  HTTP  errors,  but  that  does  not  include most 4xx
              response codes such as 404. If you want to retry on all response
              codes  that indicate HTTP errors (4xx and 5xx) then combine with
              -f, --fail.

              Added in 7.71.0.

       --retry-connrefused
              In addition to the other conditions, consider ECONNREFUSED as  a
              transient  error  too  for --retry. This option is used together
              with --retry.

              Added in 7.52.0.

       --retry-delay <seconds>
              Make curl sleep this amount of time before  each  retry  when  a
              transfer  has  failed  with  a  transient  error (it changes the
              default backoff time algorithm between retries). This option  is
              only  interesting if --retry is also used. Setting this delay to
              zero will make curl use the default backoff time.

              If this option is used several times, the last one will be used.

              Added in 7.12.3.

       --retry-max-time <seconds>
              The  retry  timer  is  reset  before the first transfer attempt.
              Retries will be done as usual (see --retry) as long as the timer
              hasn't reached this given limit. Notice that if the timer hasn't
              reached the limit, the request will be made and  while  perform-
              ing,  it may take longer than this given time period. To limit a
              single request's maximum time, use  -m,  --max-time.   Set  this
              option to zero to not timeout retries.

              If this option is used several times, the last one will be used.

              Added in 7.12.3.

       --retry <num>
              If a transient error is returned when curl tries  to  perform  a
              transfer,  it  will retry this number of times before giving up.
              Setting the number to 0 makes curl do no retries (which  is  the
              default).  Transient  error  means either: a timeout, an FTP 4xx
              response code or an HTTP 408, 429, 500, 502, 503 or 504 response
              code.

              When  curl  is about to retry a transfer, it will first wait one
              second and then for all forthcoming retries it will  double  the
              waiting  time until it reaches 10 minutes which then will be the
              delay between the rest of the retries.  By  using  --retry-delay
              you   disable  this  exponential  backoff  algorithm.  See  also
              --retry-max-time to limit the total time allowed for retries.

              Since curl  7.66.0,  curl  will  comply  with  the  Retry-After:
              response  header  if  one  was present to know when to issue the
              next retry.

              If this option is used several times, the last one will be used.

              Added in 7.12.3.

       --sasl-authzid <identity>
              Use  this  authorisation  identity  (authzid), during SASL PLAIN
              authentication,  in  addition  to  the  authentication  identity
              (authcid) as specified by -u, --user.

              If  the  option  isn't  specified,  the  server  will derive the
              authzid from the authcid, but if specified, and depending on the
              server  implementation,  it may be used to access another user's
              inbox, that the user has been granted access  to,  or  a  shared
              mailbox for example.

              Added in 7.66.0.

       --sasl-ir
              Enable initial response in SASL authentication.

              Added in 7.31.0.

       --service-name <name>
              This option allows you to change the service name for SPNEGO.

              Examples:    --negotiate    --service-name   sockd   would   use
              sockd/server-name.

              Added in 7.43.0.

       -S, --show-error
              When used with -s, --silent, it makes curl show an error message
              if it fails.

              See also --no-progress-meter.

       -s, --silent
              Silent  or  quiet  mode. Don't show progress meter or error mes-
              sages.  Makes Curl mute. It will still output the data  you  ask
              for, potentially even to the terminal/stdout unless you redirect
              it.

              Use -S, --show-error in  addition  to  this  option  to  disable
              progress meter but still show error messages.

              See also -v, --verbose, --stderr and --no-progress-meter.

       --socks4 <host[:port]>
              Use the specified SOCKS4 proxy. If the port number is not speci-
              fied, it is assumed at port 1080.

              This option overrides any previous use of -x, --proxy,  as  they
              are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can specify a
              socks4 proxy with -x, --proxy using a socks4:// protocol prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS proxy at
              the same time -x, --proxy is used with an HTTP/HTTPS  proxy.  In
              such a case curl first connects to the SOCKS proxy and then con-
              nects (through SOCKS) to the HTTP or HTTPS proxy.

              If this option is used several times, the last one will be used.

              Added in 7.15.2.

       --socks4a <host[:port]>
              Use the specified SOCKS4a proxy. If the port number is not spec-
              ified, it is assumed at port 1080.

              This option overrides any previous use of -x, --proxy,  as  they
              are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can specify a
              socks4a proxy with -x, --proxy using a socks4a:// protocol  pre-
              fix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS proxy at
              the same time -x, --proxy is used with an HTTP/HTTPS  proxy.  In
              such a case curl first connects to the SOCKS proxy and then con-
              nects (through SOCKS) to the HTTP or HTTPS proxy.

              If this option is used several times, the last one will be used.

              Added in 7.18.0.

       --socks5-basic
              Tells curl to use username/password authentication when connect-
              ing to a SOCKS5 proxy.  The username/password authentication  is
              enabled  by  default.   Use  --socks5-gssapi  to  force  GSS-API
              authentication to SOCKS5 proxies.

              Added in 7.55.0.

       --socks5-gssapi-nec
              As part of the GSS-API negotiation a protection mode is  negoti-
              ated.  RFC  1961 says in section 4.3/4.4 it should be protected,
              but the NEC  reference  implementation  does  not.   The  option
              --socks5-gssapi-nec  allows the unprotected exchange of the pro-
              tection mode negotiation.

              Added in 7.19.4.

       --socks5-gssapi-service <name>
              The default service name for a socks server is rcmd/server-fqdn.
              This option allows you to change it.

              Examples:   --socks5  proxy-name  --socks5-gssapi-service  sockd
              would use sockd/proxy-name --socks5 proxy-name  --socks5-gssapi-
              service  sockd/real-name  would  use  sockd/real-name  for cases
              where the proxy-name does not match the principal name.

              Added in 7.19.4.

       --socks5-gssapi
              Tells curl to use GSS-API authentication when  connecting  to  a
              SOCKS5  proxy.  The GSS-API authentication is enabled by default
              (if curl is compiled with GSS-API support).  Use  --socks5-basic
              to force username/password authentication to SOCKS5 proxies.

              Added in 7.55.0.

       --socks5-hostname <host[:port]>
              Use  the  specified  SOCKS5 proxy (and let the proxy resolve the
              host name). If the port number is not specified, it  is  assumed
              at port 1080.

              This  option  overrides any previous use of -x, --proxy, as they
              are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can specify a
              socks5 hostname proxy with -x, --proxy using a socks5h:// proto-
              col prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS proxy at
              the  same  time -x, --proxy is used with an HTTP/HTTPS proxy. In
              such a case curl first connects to the SOCKS proxy and then con-
              nects (through SOCKS) to the HTTP or HTTPS proxy.

              If this option is used several times, the last one will be used.

              Added in 7.18.0.

       --socks5 <host[:port]>
              Use the specified SOCKS5 proxy  -  but  resolve  the  host  name
              locally.  If  the port number is not specified, it is assumed at
              port 1080.

              This option overrides any previous use of -x, --proxy,  as  they
              are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can specify a
              socks5 proxy with -x, --proxy using a socks5:// protocol prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS proxy at
              the same time -x, --proxy is used with an HTTP/HTTPS  proxy.  In
              such a case curl first connects to the SOCKS proxy and then con-
              nects (through SOCKS) to the HTTP or HTTPS proxy.

              If this option is used several times, the last one will be used.

              This  option (as well as --socks4) does not work with IPV6, FTPS
              or LDAP.

              Added in 7.18.0.

       -Y, --speed-limit <speed>
              If a download is slower than this given speed (in bytes per sec-
              ond)  for  speed-time seconds it gets aborted. speed-time is set
              with -y, --speed-time and is 30 if not set.

              If this option is used several times, the last one will be used.

       -y, --speed-time <seconds>
              If a download is slower than speed-limit bytes per second during
              a speed-time period, the download gets aborted. If speed-time is
              used,  the  default  speed-limit  will  be 1 unless set with -Y,
              --speed-limit.

              This option controls transfers and thus  will  not  affect  slow
              connects  etc.  If this is a concern for you, try the --connect-
              timeout option.

              If this option is used several times, the last one will be used.

       --ssl-allow-beast
              This option tells curl to not work around a security flaw in the
              SSL3 and TLS1.0 protocols known as BEAST.  If this option  isn't
              used,  the SSL layer may use workarounds known to cause interop-
              erability problems with some older SSL implementations. WARNING:
              this option loosens the SSL security, and by using this flag you
              ask for exactly that.

              Added in 7.25.0.

       --ssl-auto-client-cert
              Tell libcurl to automatically locate and use a  client  certifi-
              cate  for  authentication,  when  requested  by the server. This
              option is only supported for Schannel (the  native  Windows  SSL
              library).  Prior  to  7.77.0  this  was  the default behavior in
              libcurl with Schannel. Since the server can request any certifi-
              cate  that  supports client authentication in the OS certificate
              store it could be a privacy violation and unexpected.

              See also --proxy-ssl-auto-client-cert. Added in 7.77.0.

       --ssl-no-revoke
              (Schannel) This option tells curl to disable certificate revoca-
              tion checks.  WARNING: this option loosens the SSL security, and
              by using this flag you ask for exactly that.

              Added in 7.44.0.

       --ssl-reqd
              (FTP IMAP POP3 SMTP) Require SSL/TLS for the connection.  Termi-
              nates the connection if the server doesn't support SSL/TLS.

              This option was formerly known as --ftp-ssl-reqd.

              Added in 7.20.0.

       --ssl-revoke-best-effort
              (Schannel)  This option tells curl to ignore certificate revoca-
              tion checks when they failed due to missing/offline distribution
              points for the revocation check lists.

              Added in 7.70.0.

       --ssl  (FTP  IMAP  POP3  SMTP)  Try  to use SSL/TLS for the connection.
              Reverts to a non-secure connection if the server doesn't support
              SSL/TLS.   See also --ftp-ssl-control and --ssl-reqd for differ-
              ent levels of encryption required.

              This option was formerly known as --ftp-ssl (Added  in  7.11.0).
              That  option  name  can  still  be used but will be removed in a
              future version.

              Added in 7.20.0.

       -2, --sslv2
              (SSL) This option previously asked curl to use SSLv2, but start-
              ing  in curl 7.77.0 this instruction is ignored. SSLv2 is widely
              considered insecure (see RFC 6176).

              See also --http1.1 and --http2. -2, --sslv2  requires  that  the
              underlying  libcurl  was built to support TLS. This option over-
              rides -3, --sslv3 and -1, --tlsv1 and --tlsv1.1 and --tlsv1.2.

       -3, --sslv3
              (SSL) This option previously asked curl to use SSLv3, but start-
              ing  in curl 7.77.0 this instruction is ignored. SSLv3 is widely
              considered insecure (see RFC 7568).

              See also --http1.1 and --http2. -3, --sslv3  requires  that  the
              underlying  libcurl  was built to support TLS. This option over-
              rides -2, --sslv2 and -1, --tlsv1 and --tlsv1.1 and --tlsv1.2.

       --stderr <file>
              Redirect all writes to stderr to the specified file instead.  If
              the file name is a plain '-', it is instead written to stdout.

              If this option is used several times, the last one will be used.

              See also -v, --verbose and -s, --silent.

       --styled-output
              Enables the automatic use of bold font styles when writing  HTTP
              headers  to  the terminal. Use --no-styled-output to switch them
              off.

              Added in 7.61.0.

       --suppress-connect-headers
              When -p, --proxytunnel is used and a  CONNECT  request  is  made
              don't  output  proxy  CONNECT  response  headers. This option is
              meant to be used with -D, --dump-header or -i,  --include  which
              are  used  to  show  protocol  headers  in the output. It has no
              effect on debug options such as -v, --verbose or --trace, or any
              statistics.

              See also -D, --dump-header, -i, --include and -p, --proxytunnel.

       --tcp-fastopen
              Enable use of TCP Fast Open (RFC7413).

              Added in 7.49.0.

       --tcp-nodelay
              Turn on the TCP_NODELAY option. See the curl_easy_setopt(3)  man
              page for details about this option.

              Since  7.50.2,  curl sets this option by default and you need to
              explicitly switch it off if you don't want it on.

              Added in 7.11.2.

       -t, --telnet-option <opt=val>
              Pass options to the telnet protocol. Supported options are:

              TTYPE=<term> Sets the terminal type.

              XDISPLOC=<X display> Sets the X display location.

              NEW_ENV=<var,val> Sets an environment variable.

       --tftp-blksize <value>
              (TFTP) Set TFTP BLKSIZE option (must be >512). This is the block
              size that curl will try to use when transferring data to or from
              a TFTP server. By default 512 bytes will be used.

              If this option is used several times, the last one will be used.

              Added in 7.20.0.

       --tftp-no-options
              (TFTP) Tells curl not to send TFTP options requests.

              This  option  improves  interop with some legacy servers that do
              not acknowledge or properly implement TFTP  options.  When  this
              option is used --tftp-blksize is ignored.

              Added in 7.48.0.

       -z, --time-cond <time>
              (HTTP  FTP) Request a file that has been modified later than the
              given time and date, or one that has been modified  before  that
              time.  The <date expression> can be all sorts of date strings or
              if it doesn't match any internal ones, it is taken as a filename
              and  tries  to  get  the  modification  date (mtime) from <file>
              instead. See the curl_getdate(3) man pages for  date  expression
              details.

              Start the date expression with a dash (-) to make it request for
              a document that is older than the given date/time, default is  a
              document that is newer than the specified date/time.

              If this option is used several times, the last one will be used.

       --tls-max <VERSION>
              (SSL) VERSION defines maximum supported TLS version. The minimum
              acceptable  version  is  set  by  tlsv1.0,  tlsv1.1,  tlsv1.2 or
              tlsv1.3.

              If the connection is  done  without  TLS,  this  option  has  no
              effect. This includes QUIC-using (HTTP/3) transfers.


              default
                     Use up to recommended TLS version.

              1.0    Use up to TLSv1.0.

              1.1    Use up to TLSv1.1.

              1.2    Use up to TLSv1.2.

              1.3    Use up to TLSv1.3.

       See  also  --tlsv1.0,  --tlsv1.1,  --tlsv1.2  and  --tlsv1.3. --tls-max
       requires that the underlying libcurl was built to support TLS. Added in
       7.54.0.

       --tls13-ciphers <ciphersuite list>
              (TLS)  Specifies which cipher suites to use in the connection if
              it negotiates TLS 1.3. The list of ciphers suites  must  specify
              valid  ciphers.  Read up on TLS 1.3 cipher suite details on this
              URL:

               https://curl.se/docs/ssl-ciphers.html

              This option is currently used only when curl  is  built  to  use
              OpenSSL 1.1.1 or later. If you are using a different SSL backend
              you can try setting TLS 1.3 cipher suites by using the --ciphers
              option.

              If this option is used several times, the last one will be used.

       --tlsauthtype <type>
              Set TLS  authentication  type.  Currently,  the  only  supported
              option  is  "SRP",  for  TLS-SRP  (RFC  5054).  If --tlsuser and
              --tlspassword are specified but --tlsauthtype is not, then  this
              option  defaults to "SRP".  This option works only if the under-
              lying libcurl is built  with  TLS-SRP  support,  which  requires
              OpenSSL or GnuTLS with TLS-SRP support.

              Added in 7.21.4.

       --tlspassword
              Set  password  for use with the TLS authentication method speci-
              fied with --tlsauthtype. Requires that --tlsuser also be set.

              This doesn't work with TLS 1.3.

              Added in 7.21.4.

       --tlsuser <name>
              Set username for use with the TLS authentication  method  speci-
              fied  with  --tlsauthtype.  Requires  that --tlspassword also is
              set.

              This doesn't work with TLS 1.3.

              Added in 7.21.4.

       --tlsv1.0
              (TLS) Forces curl to use TLS version 1.0 or later when  connect-
              ing to a remote TLS server.

              In  old  versions  of  curl  this option was documented to allow
              _only_ TLS 1.0, but behavior was inconsistent depending  on  the
              TLS library. Use --tls-max if you want to set a maximum TLS ver-
              sion.

              Added in 7.34.0.

       --tlsv1.1
              (TLS) Forces curl to use TLS version 1.1 or later when  connect-
              ing to a remote TLS server.

              In  old  versions  of  curl  this option was documented to allow
              _only_ TLS 1.1, but behavior was inconsistent depending  on  the
              TLS library. Use --tls-max if you want to set a maximum TLS ver-
              sion.

              Added in 7.34.0.

       --tlsv1.2
              (TLS) Forces curl to use TLS version 1.2 or later when  connect-
              ing to a remote TLS server.

              In  old  versions  of  curl  this option was documented to allow
              _only_ TLS 1.2, but behavior was inconsistent depending  on  the
              TLS library. Use --tls-max if you want to set a maximum TLS ver-
              sion.

              Added in 7.34.0.

       --tlsv1.3
              (TLS) Forces curl to use TLS version 1.3 or later when  connect-
              ing to a remote TLS server.

              If  the  connection  is  done  without  TLS,  this option has no
              effect. This includes QUIC-using (HTTP/3) transfers.

              Note that TLS 1.3 is not supported by all TLS backends.

              Added in 7.52.0.

       -1, --tlsv1
              (SSL) Tells curl to use at least TLS version 1.x when  negotiat-
              ing  with  a  remote  TLS  server. That means TLS version 1.0 or
              higher

              See also --http1.1 and --http2. -1, --tlsv1  requires  that  the
              underlying  libcurl  was built to support TLS. This option over-
              rides --tlsv1.1 and --tlsv1.2 and --tlsv1.3.

       --tr-encoding
              (HTTP) Request a compressed Transfer-Encoding response using one
              of  the  algorithms curl supports, and uncompress the data while
              receiving it.

              Added in 7.21.6.

       --trace-ascii <file>
              Enables a full trace dump of all  incoming  and  outgoing  data,
              including descriptive information, to the given output file. Use
              "-" as filename to have the output sent to stdout.

              This is very similar to --trace, but leaves out the hex part and
              only  shows  the ASCII part of the dump. It makes smaller output
              that might be easier to read for untrained humans.

              If this option is used several times, the last one will be used.

              This option overrides --trace and -v, --verbose.

       --trace-time
              Prepends  a  time  stamp to each trace or verbose line that curl
              displays.

              Added in 7.14.0.

       --trace <file>
              Enables a full trace dump of all  incoming  and  outgoing  data,
              including descriptive information, to the given output file. Use
              "-" as filename to have the output sent to stdout.  Use  "%"  as
              filename to have the output sent to stderr.

              If this option is used several times, the last one will be used.

              This option overrides -v, --verbose and --trace-ascii.

       --unix-socket <path>
              (HTTP) Connect through this Unix domain socket, instead of using
              the network.

              Added in 7.40.0.

       -T, --upload-file <file>
              This  transfers  the  specified local file to the remote URL. If
              there is no file part in the specified URL, curl will append the
              local file name. NOTE that you must use a trailing / on the last
              directory to really prove to Curl that there is no file name  or
              curl will think that your last directory name is the remote file
              name to use. That will most likely cause the upload operation to
              fail. If this is used on an HTTP(S) server, the PUT command will
              be used.

              Use the file name "-" (a single dash) to use stdin instead of  a
              given  file.   Alternately,  the file name "." (a single period)
              may be specified instead of "-" to  use  stdin  in  non-blocking
              mode  to  allow  reading  server  output  while  stdin  is being
              uploaded.

              You can specify one -T, --upload-file for each URL on  the  com-
              mand  line.  Each -T, --upload-file + URL pair specifies what to
              upload and to where. curl also supports "globbing"  of  the  -T,
              --upload-file  argument,  meaning  that  you can upload multiple
              files to a single URL by using the same URL globbing style  sup-
              ported in the URL, like this:

               curl --upload-file "{file1,file2}" http://www.example.com

              or even

               curl -T "img[1-1000].png" ftp://ftp.example.com/upload/

              When  uploading  to an SMTP server: the uploaded data is assumed
              to be RFC 5322 formatted. It has to feature the necessary set of
              headers  and  mail  body formatted correctly by the user as curl
              will not transcode nor encode it further in any way.

       --url <url>
              Specify a URL to fetch. This option is  mostly  handy  when  you
              want to specify URL(s) in a config file.

              If  the given URL is missing a scheme name (such as "http://" or
              "ftp://" etc) then curl will make a guess based on the host.  If
              the  outermost  sub-domain  name  matches DICT, FTP, IMAP, LDAP,
              POP3 or SMTP then that protocol will  be  used,  otherwise  HTTP
              will be used. Since 7.45.0 guessing can be disabled by setting a
              default protocol, see --proto-default for details.

              This option may be used any number of times.  To  control  where
              this  URL  is written, use the -o, --output or the -O, --remote-
              name options.

              Warning: On Windows, particular file://  accesses  can  be  con-
              verted to network accesses by the operating system. Beware!

       -B, --use-ascii
              (FTP  LDAP)  Enable  ASCII  transfer.  For FTP, this can also be
              enforced by using a URL that ends with  ";type=A".  This  option
              causes data sent to stdout to be in text mode for win32 systems.

       -A, --user-agent <name>
              (HTTP) Specify the User-Agent string to send to the HTTP server.
              To  encode blanks in the string, surround the string with single
              quote marks. This header can also be set with the  -H,  --header
              or the --proxy-header options.

              If  you give an empty argument to -A, --user-agent (""), it will
              remove the header completely from the request. If you  prefer  a
              blank header, you can set it to a single space (" ").

              If this option is used several times, the last one will be used.

       -u, --user <user:password>
              Specify the user name and password to use for server authentica-
              tion. Overrides -n, --netrc and --netrc-optional.

              If  you  simply  specify  the  user name, curl will prompt for a
              password.

              The user name and passwords are split up  on  the  first  colon,
              which  makes  it impossible to use a colon in the user name with
              this option. The password can, still.

              On systems where it works, curl will hide the given option argu-
              ment  from  process listings. This is not enough to protect cre-
              dentials from possibly getting seen by other users on  the  same
              system  as  they will still be visible for a brief moment before
              cleared. Such sensitive data should be  retrieved  from  a  file
              instead  or  similar  and  never used in clear text in a command
              line.

              When using Kerberos V5 with a Windows based  server  you  should
              include  the  Windows domain name in the user name, in order for
              the server to successfully obtain  a  Kerberos  Ticket.  If  you
              don't then the initial authentication handshake may fail.

              When  using  NTLM,  the user name can be specified simply as the
              user name, without the domain, if there is a single  domain  and
              forest in your setup for example.

              To  specify  the domain name use either Down-Level Logon Name or
              UPN (User Principal Name) formats. For example, EXAMPLE\user and
              user@example.com respectively.

              If  you  use a Windows SSPI-enabled curl binary and perform Ker-
              beros V5, Negotiate, NTLM or Digest authentication then you  can
              tell  curl  to select the user name and password from your envi-
              ronment by specifying a single colon with this option: "-u :".

              If this option is used several times, the last one will be used.

       -v, --verbose
              Makes  curl  verbose  during the operation. Useful for debugging
              and seeing what's going on "under the  hood".  A  line  starting
              with  '>'  means  "header  data" sent by curl, '<' means "header
              data" received by curl that is hidden in  normal  cases,  and  a
              line starting with '*' means additional info provided by curl.

              If you only want HTTP headers in the output, -i, --include might
              be the option you're looking for.

              If you think this option still doesn't give you enough  details,
              consider using --trace or --trace-ascii instead.

              Use -s, --silent to make curl really quiet.

              See  also  -i,  --include.  This  option  overrides  --trace and
              --trace-ascii.

       -V, --version
              Displays information about curl and the libcurl version it uses.

              The  first  line  includes the full version of curl, libcurl and
              other 3rd party libraries linked with the executable.

              The second line (starts with "Protocols:") shows  all  protocols
              that libcurl reports to support.

              The third line (starts with "Features:") shows specific features
              libcurl reports to offer. Available features include:

              alt-svc
                     Support for the Alt-Svc: header is provided.

              AsynchDNS
                     This curl uses asynchronous name  resolves.  Asynchronous
                     name  resolves can be done using either the c-ares or the
                     threaded resolver backends.

              brotli Support for automatic brotli compression over HTTP(S).

              CharConv
                     curl was built with support for character set conversions
                     (like EBCDIC)

              Debug  This  curl  uses a libcurl built with Debug. This enables
                     more error-tracking and memory debugging etc.  For  curl-
                     developers only!

              gsasl  The  built-in  SASL authentication includes extensions to
                     support SCRAM because libcurl was built with libgsasl.

              GSS-API
                     GSS-API is supported.

              HSTS   HSTS support is present.

              HTTP2  HTTP/2 support has been built-in.

              HTTP3  HTTP/3 support has been built-in.

              HTTPS-proxy
                     This curl is built to support HTTPS proxy.

              IDN    This curl supports IDN - international domain names.

              IPv6   You can use IPv6 with this.

              Kerberos
                     Kerberos V5 authentication is supported.

              Largefile
                     This curl supports transfers of large files, files larger
                     than 2GB.

              libz   Automatic decompression (via gzip, deflate) of compressed
                     files over HTTP is supported.

              Metalink
                     This curl supports Metalink.

              MultiSSL
                     This curl supports multiple TLS backends.

              NTLM   NTLM authentication is supported.

              NTLM_WB
                     NTLM delegation to winbind helper is supported.

              PSL    PSL is short for Public Suffix List and means  that  this
                     curl  has  been  built  with knowledge about "public suf-
                     fixes".

              SPNEGO SPNEGO authentication is supported.

              SSL    SSL versions of various protocols are supported, such  as
                     HTTPS, FTPS, POP3S and so on.

              SSPI   SSPI is supported.

              TLS-SRP
                     SRP  (Secure Remote Password) authentication is supported
                     for TLS.

              TrackMemory
                     Debug memory tracking is supported.

              Unicode
                     Unicode support on Windows.

              UnixSockets
                     Unix sockets support is provided.

              zstd   Automatic decompression (via zstd)  of  compressed  files
                     over HTTP is supported.

       -w, --write-out <format>
              Make curl display information on stdout after a completed trans-
              fer. The format is a string that may contain  plain  text  mixed
              with  any  number of variables. The format can be specified as a
              literal "string", or you can have curl read the  format  from  a
              file  with  "@filename" and to tell curl to read the format from
              stdin you write "@-".

              The variables present in the output format will  be  substituted
              by  the  value or text that curl thinks fit, as described below.
              All variables are specified as %{variable_name} and to output  a
              normal  % you just write them as %%. You can output a newline by
              using \n, a carriage return with \r and a tab space with \t.

              The output will be written to standard output, but this  can  be
              switched to standard error by using %{stderr}.

              NOTE: The %-symbol is a special symbol in the win32-environment,
              where all occurrences of %  must  be  doubled  when  using  this
              option.

              The variables available are:

              content_type   The  Content-Type  of  the requested document, if
                             there was any.

              errormsg       The error message. (Added in 7.75.0)

              exitcode       The numerical exitcode of the transfer. (Added in
                             7.75.0)

              filename_effective
                             The  ultimate  filename  that curl writes out to.
                             This is only meaningful if curl is told to  write
                             to  a  file  with  the  -O,  --remote-name or -o,
                             --output option. It's most useful in  combination
                             with  the -J, --remote-header-name option. (Added
                             in 7.26.0)

              ftp_entry_path The initial path curl ended up in when logging on
                             to the remote FTP server. (Added in 7.15.4)

              http_code      The numerical response code that was found in the
                             last retrieved HTTP(S)  or  FTP(s)  transfer.  In
                             7.18.2  the alias response_code was added to show
                             the same info.

              http_connect   The numerical code that was  found  in  the  last
                             response   (from  a  proxy)  to  a  curl  CONNECT
                             request. (Added in 7.12.4)

              http_version   The  http  version  that  was  effectively  used.
                             (Added in 7.50.0)

              json           A JSON object with all available keys.

              local_ip       The  IP  address  of  the  local  end of the most
                             recently done connection - can be either IPv4  or
                             IPv6 (Added in 7.29.0)

              local_port     The  local  port number of the most recently done
                             connection (Added in 7.29.0)

              method         The http method used  in  the  most  recent  HTTP
                             request (Added in 7.72.0)

              num_connects   Number  of new connects made in the recent trans-
                             fer. (Added in 7.12.3)

              num_headers    The number of response headers in the most recent
                             request (restarted at each
                              redirect).  Note  that  the status line IS NOT a
                             header. (Added in 7.73.0)

              num_redirects  Number of redirects that  were  followed  in  the
                             request. (Added in 7.12.3)

              onerror        The  rest  of  the  output  is  only shown if the
                             transfer returned  a  non-zero  error  (Added  in
                             7.75.0)

              proxy_ssl_verify_result
                             The result of the HTTPS proxy's SSL peer certifi-
                             cate verification that was requested. 0 means the
                             verification was successful. (Added in 7.52.0)

              redirect_url   When an HTTP request was made without -L, --loca-
                             tion to follow redirects (or when --max-redir  is
                             met),  this  variable  will show the actual URL a
                             redirect would have gone to. (Added in 7.18.2)

              referer        The Referer: header, if there was any. (Added  in
                             7.76.0)

              remote_ip      The  remote  IP address of the most recently done
                             connection - can be either IPv4 or IPv6 (Added in
                             7.29.0)

              remote_port    The  remote port number of the most recently done
                             connection (Added in 7.29.0)

              response_code  The numerical response code that was found in the
                             last  transfer  (formerly  known as "http_code").
                             (Added in 7.18.2)

              scheme         The URL scheme (sometimes called  protocol)  that
                             was effectively used (Added in 7.52.0)

              size_download  The total amount of bytes that were downloaded.

              size_header    The total amount of bytes of the downloaded head-
                             ers.

              size_request   The total amount of bytes that were sent  in  the
                             HTTP request.

              size_upload    The total amount of bytes that were uploaded.

              speed_download The average download speed that curl measured for
                             the complete download. Bytes per second.

              speed_upload   The average upload speed that curl  measured  for
                             the complete upload. Bytes per second.

              ssl_verify_result
                             The  result of the SSL peer certificate verifica-
                             tion that was requested. 0 means the verification
                             was successful. (Added in 7.19.0)

              stderr         From  this  point  on, the -w, --write-out output
                             will be written  to  standard  error.  (Added  in
                             7.63.0)

              stdout         From  this  point  on, the -w, --write-out output
                             will be written to standard output.  This is  the
                             default,  but  can  be  used to switch back after
                             switching to stderr.  (Added in 7.63.0)

              time_appconnect
                             The time, in seconds,  it  took  from  the  start
                             until  the  SSL/SSH/etc  connect/handshake to the
                             remote host was completed. (Added in 7.19.0)

              time_connect   The time, in seconds,  it  took  from  the  start
                             until  the  TCP  connect  to  the remote host (or
                             proxy) was completed.

              time_namelookup
                             The time, in seconds,  it  took  from  the  start
                             until the name resolving was completed.

              time_pretransfer
                             The  time,  in  seconds,  it  took from the start
                             until the file transfer was just about to  begin.
                             This includes all pre-transfer commands and nego-
                             tiations that are specific to the particular pro-
                             tocol(s) involved.

              time_redirect  The time, in seconds, it took for all redirection
                             steps including name lookup, connect, pretransfer
                             and  transfer  before  the  final transaction was
                             started. time_redirect shows the complete  execu-
                             tion  time  for  multiple redirections. (Added in
                             7.12.3)

              time_starttransfer
                             The time, in seconds,  it  took  from  the  start
                             until  the first byte was just about to be trans-
                             ferred. This includes time_pretransfer  and  also
                             the  time  the  server  needed  to  calculate the
                             result.

              time_total     The total time, in seconds, that the full  opera-
                             tion lasted.

              url            The URL that was fetched. (Added in 7.75.0)

              urlnum         The URL index number of this transfer, 0-indexed.
                             (Added in 7.75.0)

              url_effective  The URL that was fetched last. This is most mean-
                             ingful  if  you've  told curl to follow location:
                             headers.

              If this option is used several times, the last one will be used.

       --xattr
              When  saving  output  to a file, this option tells curl to store
              certain file metadata in extended  file  attributes.  Currently,
              the URL is stored in the xdg.origin.url attribute and, for HTTP,
              the content type is stored in the mime_type  attribute.  If  the
              file  system  does not support extended attributes, a warning is
              issued.


FILES

       ~/.curlrc
              Default config file, see -K, --config for details.


ENVIRONMENT

       The environment variables can be specified in lower case or upper case.
       The lower case version has precedence. http_proxy is an exception as it
       is only available in lower case.

       Using an environment variable to set the proxy has the same  effect  as
       using the -x, --proxy option.


       http_proxy [protocol://]<host>[:port]
              Sets the proxy server to use for HTTP.

       HTTPS_PROXY [protocol://]<host>[:port]
              Sets the proxy server to use for HTTPS.

       [url-protocol]_PROXY [protocol://]<host>[:port]
              Sets  the proxy server to use for [url-protocol], where the pro-
              tocol is a protocol that curl supports and  as  specified  in  a
              URL. FTP, FTPS, POP3, IMAP, SMTP, LDAP etc.

       ALL_PROXY [protocol://]<host>[:port]
              Sets  the  proxy  server to use if no protocol-specific proxy is
              set.

       NO_PROXY <comma-separated list of hosts/domains>
              list of host names that shouldn't go through any proxy.  If  set
              to an asterisk '*' only, it matches all hosts. Each name in this
              list is matched as either a domain name which contains the host-
              name, or the hostname itself.

              This  environment  variable  disables use of the proxy even when
              specified   with   the   -x,    --proxy    option.    That    is
              NO_PROXY=direct.example.com   curl  -x  http://proxy.example.com
              http://direct.example.com accesses the target URL directly,  and
              NO_PROXY=direct.example.com   curl  -x  http://proxy.example.com
              http://somewhere.example.com accesses the target URL through the
              proxy.

              The  list  of  host  names  can  also  be  include  numerical IP
              addresses, and  IPv6  versions  should  then  be  given  without
              enclosing brackets.

              IPv6  numerical  addresses are compared as strings, so they will
              only match if the representations are the  same:  "::1"  is  the
              same as "::0:1" but they don't match.

       CURL_SSL_BACKEND <TLS backend>
              If  curl  was built with support for "MultiSSL", meaning that it
              has built-in support for more than one TLS backend,  this  envi-
              ronment  variable can be set to the case insensitive name of the
              particular backend to use when curl is invoked. Setting  a  name
              that  isn't  a built-in alternative will make curl stay with the
              default.

              SSL backend names (case-insensitive):  bearssl,  gnutls,  gskit,
              mbedtls, mesalink, nss, openssl, rustls, schannel, secure-trans-
              port, wolfssl

       QLOGDIR <directory name>
              If curl was built with HTTP/3 support, setting this  environment
              variable  to  a  local directory will make curl produce qlogs in
              that directory, using file names  named  after  the  destination
              connection  id  (in  hex).  Do  note that these files can become
              rather large. Works with both QUIC backends.

       SSLKEYLOGFILE <file name>
              If you set this environment variable to a file name,  curl  will
              store TLS secrets from its connections in that file when invoked
              to enable you to analyze the TLS traffic in real time using net-
              work analyzing tools such as Wireshark. This works with the fol-
              lowing TLS backends: OpenSSL, libressl, BoringSSL,  GnuTLS,  NSS
              and wolfSSL.


PROXY PROTOCOL PREFIXES

       Since  curl  version  7.21.7,  the proxy string may be specified with a
       protocol:// prefix to specify alternative proxy protocols.

       If no protocol is specified in  the  proxy  string  or  if  the  string
       doesn't  match  a  supported  one, the proxy will be treated as an HTTP
       proxy.

       The supported proxy protocol prefixes are as follows:

       http://
              Makes it use it as an HTTP proxy. The default if no scheme  pre-
              fix is used.

       https://
              Makes it treated as an HTTPS proxy.

       socks4://
              Makes it the equivalent of --socks4

       socks4a://
              Makes it the equivalent of --socks4a

       socks5://
              Makes it the equivalent of --socks5

       socks5h://
              Makes it the equivalent of --socks5-hostname


EXIT CODES

       There  are  a  bunch  of  different error codes and their corresponding
       error messages that may appear during bad conditions. At  the  time  of
       this writing, the exit codes are:

       1      Unsupported protocol. This build of curl has no support for this
              protocol.

       2      Failed to initialize.

       3      URL malformed. The syntax was not correct.

       4      A feature or option that  was  needed  to  perform  the  desired
              request  was  not  enabled  or was explicitly disabled at build-
              time. To make curl able to do this, you  probably  need  another
              build of libcurl!

       5      Couldn't  resolve  proxy.  The  given  proxy  host  could not be
              resolved.

       6      Couldn't resolve host. The given remote host was not resolved.

       7      Failed to connect to host.

       8      Weird server reply. The server sent data curl couldn't parse.

       9      FTP access denied. The server denied login or denied  access  to
              the  particular  resource or directory you wanted to reach. Most
              often you tried to change to a directory that doesn't  exist  on
              the server.

       10     FTP  accept failed. While waiting for the server to connect back
              when an active FTP session is used, an error code was sent  over
              the control connection or similar.

       11     FTP  weird PASS reply. Curl couldn't parse the reply sent to the
              PASS request.

       12     During an active FTP session while waiting  for  the  server  to
              connect back to curl, the timeout expired.

       13     FTP  weird PASV reply, Curl couldn't parse the reply sent to the
              PASV request.

       14     FTP weird 227 format.  Curl  couldn't  parse  the  227-line  the
              server sent.

       15     FTP  can't  get host. Couldn't resolve the host IP we got in the
              227-line.

       16     HTTP/2 error. A problem was detected in the HTTP2 framing layer.
              This is somewhat generic and can be one out of several problems,
              see the error message for details.

       17     FTP couldn't set binary.  Couldn't  change  transfer  method  to
              binary.

       18     Partial file. Only a part of the file was transferred.

       19     FTP  couldn't download/access the given file, the RETR (or simi-
              lar) command failed.

       21     FTP quote error. A quote command returned error from the server.

       22     HTTP  page  not  retrieved.  The  requested url was not found or
              returned another error with the HTTP error  code  being  400  or
              above. This return code only appears if -f, --fail is used.

       23     Write  error.  Curl couldn't write data to a local filesystem or
              similar.

       25     FTP couldn't STOR file. The server denied  the  STOR  operation,
              used for FTP uploading.

       26     Read error. Various reading problems.

       27     Out of memory. A memory allocation request failed.

       28     Operation  timeout.  The  specified  time-out period was reached
              according to the conditions.

       30     FTP PORT failed. The PORT command failed. Not  all  FTP  servers
              support  the  PORT  command,  try  doing  a  transfer using PASV
              instead!

       31     FTP couldn't use REST. The REST command failed. This command  is
              used for resumed FTP transfers.

       33     HTTP range error. The range "command" didn't work.

       34     HTTP post error. Internal post-request generation error.

       35     SSL connect error. The SSL handshaking failed.

       36     Bad  download resume. Couldn't continue an earlier aborted down-
              load.

       37     FILE couldn't read file. Failed to open the file. Permissions?

       38     LDAP cannot bind. LDAP bind operation failed.

       39     LDAP search failed.

       41     Function not found. A required LDAP function was not found.

       42     Aborted by callback. An application told curl to abort the oper-
              ation.

       43     Internal error. A function was called with a bad parameter.

       45     Interface  error.  A  specified  outgoing interface could not be
              used.

       47     Too many redirects. When following redirects, curl hit the maxi-
              mum amount.

       48     Unknown  option  specified  to  libcurl. This indicates that you
              passed a weird option to curl that was passed on to libcurl  and
              rejected. Read up in the manual!

       49     Malformed telnet option.

       51     The peer's SSL certificate or SSH MD5 fingerprint was not OK.

       52     The  server  didn't  reply anything, which here is considered an
              error.

       53     SSL crypto engine not found.

       54     Cannot set SSL crypto engine as default.

       55     Failed sending network data.

       56     Failure in receiving network data.

       58     Problem with the local certificate.

       59     Couldn't use specified SSL cipher.

       60     Peer certificate cannot be authenticated with known CA  certifi-
              cates.

       61     Unrecognized transfer encoding.

       62     Invalid LDAP URL.

       63     Maximum file size exceeded.

       64     Requested FTP SSL level failed.

       65     Sending the data requires a rewind that failed.

       66     Failed to initialise SSL Engine.

       67     The  user  name,  password, or similar was not accepted and curl
              failed to log in.

       68     File not found on TFTP server.

       69     Permission problem on TFTP server.

       70     Out of disk space on TFTP server.

       71     Illegal TFTP operation.

       72     Unknown TFTP transfer ID.

       73     File already exists (TFTP).

       74     No such user (TFTP).

       75     Character conversion failed.

       76     Character conversion functions required.

       77     Problem with reading the SSL CA cert (path? access rights?).

       78     The resource referenced in the URL does not exist.

       79     An unspecified error occurred during the SSH session.

       80     Failed to shut down the SSL connection.

       82     Could not load CRL file,  missing  or  wrong  format  (added  in
              7.19.0).

       83     Issuer check failed (added in 7.19.0).

       84     The FTP PRET command failed

       85     RTSP: mismatch of CSeq numbers

       86     RTSP: mismatch of Session Identifiers

       87     unable to parse FTP file list

       88     FTP chunk callback reported error

       89     No connection available, the session will be queued

       90     SSL public key does not matched pinned public key

       91     Invalid SSL certificate status.

       92     Stream error in HTTP/2 framing layer.

       93     An API function was called from inside a callback.

       94     An authentication function returned an error.

       95     A  problem  was  detected  in the HTTP/3 layer. This is somewhat
              generic and can be one out of several problems,  see  the  error
              message for details.

       96     QUIC  connection  error.  This  error  may  be  caused by an SSL
              library error. QUIC is the protocol used for HTTP/3 transfers.

       XX     More error codes will appear here in future releases. The exist-
              ing ones are meant to never change.


AUTHORS / CONTRIBUTORS

       Daniel  Stenberg is the main author, but the whole list of contributors
       is found in the separate THANKS file.


WWW

       https://curl.se


SEE ALSO

       ftp(1), wget(1)



Curl 7.77.0                    November 16, 2016                       curl(1)

curl 7.77.0 - Generated Sun May 30 19:14:45 CDT 2021
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