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zsync(1)                         File Transfer                        zsync(1)




NAME

       zsync - Partial/differential file download client over HTTP


SYNTAX

       zsync  [  -u url ] [ -i inputfile ] [ -o outputfile ] [ { -s | -q } ] [
       -k file.zsync ] [ -A hostname=username:password ] { filename | url }

       zsync -V


DESCRIPTION

       Downloads a file over HTTP. zsync uses  a  control  file  to  determine
       whether any blocks in the file are already known to the downloader, and
       only downloads the new blocks.

       Either a filename or a URL can be given on the command line -  this  is
       the  path  of the control file for the download, which normally has the
       name of the actual file to downlaod with .zsync  appended.  (To  create
       this  .zsync  file  you have to have a copy of the target file, so this
       file should be generated by the person providing the download).

       zsync downloads to your current directory. It looks for any file in the
       directory of the same name as the file to download. If it finds one, it
       assumes that this is an earlier or incomplete version of the  new  file
       to  download,  and  scans  this  file for any blocks that it can use to
       build the target file. (It also looks for a file of the same name  with
       .part  appended,  so  it will automatically find previously interrupted
       zsync downloads and reuse the data already downloaded. If you know that
       the local file to use as input has a different name, you must use -i)

       zsync  retrieves  the rest of the target file over HTTP. Once the down-
       load is finished, the old version (if the new file wants the same name)
       is moved aside (a .zs-old extension is appended). The modification time
       of the file is set to be the same as the remote source file (if  speci-
       fied in the .zsync).


OPTIONS

       -A hostname=username:password
              Specifies  a  username  and  password  to be used with the given
              hostname. -A can be used multiple times  (with  different  host-
              names), in cases where e.g. the download servers (there could be
              different auth details for different servers - and  zsync  never
              assumes that your password should be sent to a server other than
              the one named - otherwise redirects would be dangerous!).

       -i inputfile
              Specifies (extra) input files. inputfile is scanned to  identify
              blocks  in common with the target file and zsync uses any blocks
              found. Can be used multiple times.

       -k file.zsync
              Indicates that zsync should save the zsync file  that  it  down-
              loads,  with  the  given  filename. If that file already exists,
              then zsync will make a conditional request to  the  web  server,
              such that it will only download it again if the server's copy is
              newer. zsync will append .part to the filename  for  storing  it
              while  it  is downloading, and will only overwrite the main file
              once the download is done - and if the download is  interrupted,
              it will resume using the data in the .part file.

       -o outputfile
              Override the default output file name.

       -q     Suppress the progress bar, download rate and ETA display.

       -s     Deprecated synonym for -q.

       -u url This  specifies  the  referring  URL.  If you have a .zsync file
              locally (if you downloaded it separately, with  wget,  say)  and
              the  .zsync  file  contains  a relative URL, you need to specify
              where you got the .zsync file from so  that  zsync  knows  which
              server  and  path  to  use for the rest of the download (this is
              analogous to adding a <base href="..."> to a downloaded web page
              to make the links work).

       -V     Prints the version of zsync.


FILES


ENVIRONMENT VARIABLES

       http_proxy
              Should  be the [http://]hostname:port for your web proxy, if one
              is required to access the target web server(s).


EXAMPLES

       zsync                                                                -i
       /var/lib/apt/lists/ftp.uk.debian.org_debian_dists_sarge_main_binary-i386_Pack-
       ageshttp://zsync.moria.org.uk/s/sarge/Packages.zsync



AUTHORS

       Colin Phipps <cph@moria.org.uk>


SEE ALSO

       zsyncmake(1)



Colin Phipps                          0.6                             zsync(1)

zsync 0.6 - Generated Sun Jan 25 06:35:37 CST 2009
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