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grep(1)                          User Commands                         grep(1)




NAME

       grep, egrep, fgrep - print lines that match patterns


SYNOPSIS

       grep [OPTION...] PATTERNS [FILE...]
       grep [OPTION...] -e PATTERNS ... [FILE...]
       grep [OPTION...] -f PATTERN_FILE ... [FILE...]


DESCRIPTION

       grep  searches  for  PATTERNS  in  each  FILE.  PATTERNS is one or more
       patterns separated by newline characters, and  grep  prints  each  line
       that  matches a pattern.  Typically PATTERNS should be quoted when grep
       is used in a shell command.

       A FILE of "-"  stands  for  standard  input.   If  no  FILE  is  given,
       recursive  searches  examine  the  working  directory, and nonrecursive
       searches read standard input.

       In addition, the variant programs egrep  and  fgrep  are  the  same  as
       grep -E  and grep -F, respectively.  These variants are deprecated, but
       are provided for backward compatibility.


OPTIONS

   Generic Program Information
       --help Output a usage message and exit.

       -V, --version
              Output the version number of grep and exit.

   Pattern Syntax
       -E, --extended-regexp
              Interpret PATTERNS as extended regular  expressions  (EREs,  see
              below).

       -F, --fixed-strings
              Interpret PATTERNS as fixed strings, not regular expressions.

       -G, --basic-regexp
              Interpret  PATTERNS  as  basic  regular  expressions  (BREs, see
              below).  This is the default.

       -P, --perl-regexp
              Interpret I<PATTERNS>  as  Perl-compatible  regular  expressions
              (PCREs).   This option is experimental when combined with the -z
              (--null-data) option, and grep  -P  may  warn  of  unimplemented
              features.

   Matching Control
       -e PATTERNS, --regexp=PATTERNS
              Use  PATTERNS  as the patterns.  If this option is used multiple
              times or is combined with the -f (--file) option, search for all
              patterns  given.   This  option can be used to protect a pattern
              beginning with "-".

       -f FILE, --file=FILE
              Obtain patterns from FILE, one per line.  If this option is used
              multiple  times  or  is  combined with the -e (--regexp) option,
              search for all patterns given.  The  empty  file  contains  zero
              patterns, and therefore matches nothing.

       -i, --ignore-case
              Ignore  case  distinctions  in  patterns and input data, so that
              characters that differ only in case match each other.

       --no-ignore-case
              Do not ignore case distinctions  in  patterns  and  input  data.
              This is the default.  This option is useful for passing to shell
              scripts that already use -i, to cancel its effects  because  the
              two options override each other.

       -v, --invert-match
              Invert the sense of matching, to select non-matching lines.

       -w, --word-regexp
              Select  only  those  lines  containing  matches  that form whole
              words.  The test is that the matching substring must  either  be
              at  the  beginning  of  the  line,  or  preceded  by  a non-word
              constituent character.  Similarly, it must be either at the  end
              of  the  line  or  followed by a non-word constituent character.
              Word-constituent  characters  are  letters,  digits,   and   the
              underscore.   This option has no effect if -x is also specified.

       -x, --line-regexp
              Select only those matches that exactly  match  the  whole  line.
              For  a  regular  expression pattern, this is like parenthesizing
              the pattern and then surrounding it with ^ and $.

       -y     Obsolete synonym for -i.

   General Output Control
       -c, --count
              Suppress normal output; instead print a count of matching  lines
              for  each  input  file.  With the -v, --invert-match option (see
              below), count non-matching lines.

       --color[=WHEN], --colour[=WHEN]
              Surround  the  matched  (non-empty)  strings,  matching   lines,
              context  lines,  file  names,  line  numbers,  byte offsets, and
              separators (for fields and groups of context lines) with  escape
              sequences  to display them in color on the terminal.  The colors
              are  defined  by  the  environment  variable  GREP_COLORS.   The
              deprecated  environment  variable GREP_COLOR is still supported,
              but its setting does not have priority.  WHEN is never,  always,
              or auto.

       -L, --files-without-match
              Suppress  normal  output;  instead  print the name of each input
              file from which no output would normally have been printed.

       -l, --files-with-matches
              Suppress normal output; instead print the  name  of  each  input
              file  from  which  output  would  normally  have  been  printed.
              Scanning each input file stops upon first match.

       -m NUM, --max-count=NUM
              Stop reading a file after NUM matching lines.  If the  input  is
              standard  input  from a regular file, and NUM matching lines are
              output, grep ensures that the standard input  is  positioned  to
              just  after the last matching line before exiting, regardless of
              the presence of trailing context lines.  This enables a  calling
              process  to resume a search.  When grep stops after NUM matching
              lines, it outputs any trailing context lines.  When  the  -c  or
              --count  option  is  also  used,  grep  does  not output a count
              greater than NUM.  When the -v or --invert-match option is  also
              used, grep stops after outputting NUM non-matching lines.

       -o, --only-matching
              Print  only  the  matched  (non-empty) parts of a matching line,
              with each such part on a separate output line.

       -q, --quiet, --silent
              Quiet;  do  not  write  anything  to  standard   output.    Exit
              immediately  with  zero status if any match is found, even if an
              error was detected.  Also see the -s or --no-messages option.

       -s, --no-messages
              Suppress error messages about nonexistent or unreadable files.

   Output Line Prefix Control
       -b, --byte-offset
              Print the 0-based byte offset within the input file before  each
              line of output.  If -o (--only-matching) is specified, print the
              offset of the matching part itself.

       -H, --with-filename
              Print the file name for each match.  This is  the  default  when
              there is more than one file to search.  This is a GNU extension.

       -h, --no-filename
              Suppress the prefixing of file names on  output.   This  is  the
              default  when there is only one file (or only standard input) to
              search.

       --label=LABEL
              Display input actually  coming  from  standard  input  as  input
              coming  from  file  LABEL.  This can be useful for commands that
              transform a file's contents before  searching,  e.g.,  gzip  -cd
              foo.gz  |  grep  --label=foo -H 'some pattern'.  See also the -H
              option.

       -n, --line-number
              Prefix each line of output with the 1-based line  number  within
              its input file.

       -T, --initial-tab
              Make  sure  that the first character of actual line content lies
              on a tab stop, so that the alignment of tabs looks normal.  This
              is  useful  with  options that prefix their output to the actual
              content: -H,-n, and -b.  In order  to  improve  the  probability
              that lines from a single file will all start at the same column,
              this also causes the line number and byte offset (if present) to
              be printed in a minimum size field width.

       -Z, --null
              Output  a  zero  byte  (the  ASCII NUL character) instead of the
              character that normally follows a file name.  For example,  grep
              -lZ  outputs  a  zero  byte  after each file name instead of the
              usual newline.  This option makes the output  unambiguous,  even
              in the presence of file names containing unusual characters like
              newlines.  This option can  be  used  with  commands  like  find
              -print0,  perl  -0,  sort  -z, and xargs -0 to process arbitrary
              file names, even those that contain newline characters.

   Context Line Control
       -A NUM, --after-context=NUM
              Print NUM  lines  of  trailing  context  after  matching  lines.
              Places   a  line  containing  a  group  separator  (--)  between
              contiguous groups of matches.  With the  -o  or  --only-matching
              option, this has no effect and a warning is given.

       -B NUM, --before-context=NUM
              Print  NUM  lines  of  leading  context  before  matching lines.
              Places  a  line  containing  a  group  separator  (--)   between
              contiguous  groups  of  matches.  With the -o or --only-matching
              option, this has no effect and a warning is given.

       -C NUM, -NUM, --context=NUM
              Print NUM lines of output context.  Places a line  containing  a
              group separator (--) between contiguous groups of matches.  With
              the -o or --only-matching option,  this  has  no  effect  and  a
              warning is given.

       --group-separator=SEP
              When  -A,  -B, or -C are in use, print SEP instead of -- between
              groups of lines.

       --no-group-separator
              When -A, -B, or -C are in use, do not print a separator  between
              groups of lines.

   File and Directory Selection
       -a, --text
              Process  a binary file as if it were text; this is equivalent to
              the --binary-files=text option.

       --binary-files=TYPE
              If a file's data or metadata indicate  that  the  file  contains
              binary  data,  assume  that  the file is of type TYPE.  Non-text
              bytes indicate binary data; these are either output  bytes  that
              are  improperly  encoded  for  the current locale, or null input
              bytes when the -z option is not given.

              By default, TYPE is binary, and  grep  suppresses  output  after
              null  input  binary  data  is  discovered, and suppresses output
              lines that contain improperly encoded data.  When some output is
              suppressed,  grep  follows  any  output  with a one-line message
              saying that a binary file matches.

              If TYPE is without-match, when grep discovers null input  binary
              data  it  assumes that the rest of the file does not match; this
              is equivalent to the -I option.

              If TYPE is text, grep processes a binary  file  as  if  it  were
              text; this is equivalent to the -a option.

              When  type  is  binary,  grep  may  treat non-text bytes as line
              terminators even without the -z  option.   This  means  choosing
              binary  versus text can affect whether a pattern matches a file.
              For example, when type is binary the pattern q$  might  match  q
              immediately  followed  by  a  null byte, even though this is not
              matched when type is text.  Conversely, when type is binary  the
              pattern . (period) might not match a null byte.

              Warning:  The  -a  option might output binary garbage, which can
              have nasty side effects if the output is a terminal and  if  the
              terminal driver interprets some of it as commands.  On the other
              hand, when reading files whose text encodings  are  unknown,  it
              can   be  helpful  to  use  -a  or  to  set  LC_ALL='C'  in  the
              environment, in order to find more matches even if  the  matches
              are unsafe for direct display.

       -D ACTION, --devices=ACTION
              If  an  input  file  is  a device, FIFO or socket, use ACTION to
              process it.  By  default,  ACTION  is  read,  which  means  that
              devices are read just as if they were ordinary files.  If ACTION
              is skip, devices are silently skipped.

       -d ACTION, --directories=ACTION
              If an input file is a directory, use ACTION to process  it.   By
              default,  ACTION is read, i.e., read directories just as if they
              were  ordinary  files.   If  ACTION  is  skip,   silently   skip
              directories.   If  ACTION  is recurse, read all files under each
              directory, recursively, following symbolic links  only  if  they
              are on the command line.  This is equivalent to the -r option.

       --exclude=GLOB
              Skip  any  command-line file with a name suffix that matches the
              pattern GLOB, using wildcard matching; a name suffix  is  either
              the  whole name, or a trailing part that starts with a non-slash
              character immediately after a  slash  (/)  in  the  name.   When
              searching  recursively, skip any subfile whose base name matches
              GLOB; the base name is the part after the last slash.  A pattern
              can  use *, ?, and [...] as wildcards, and \ to quote a wildcard
              or backslash character literally.

       --exclude-from=FILE
              Skip files whose base name matches any of  the  file-name  globs
              read  from  FILE  (using  wildcard  matching  as described under
              --exclude).

       --exclude-dir=GLOB
              Skip any command-line directory with a name suffix that  matches
              the   pattern   GLOB.   When  searching  recursively,  skip  any
              subdirectory whose base name matches GLOB.  Ignore any redundant
              trailing slashes in GLOB.

       -I     Process  a  binary  file as if it did not contain matching data;
              this is equivalent to the --binary-files=without-match option.

       --include=GLOB
              Search only files whose base name matches GLOB  (using  wildcard
              matching   as  described  under  --exclude).   If  contradictory
              --include and --exclude options are given, the last matching one
              wins.   If  no  --include  or --exclude options match, a file is
              included unless the first such option is --include.

       -r, --recursive
              Read all files  under  each  directory,  recursively,  following
              symbolic  links only if they are on the command line.  Note that
              if no file  operand  is  given,  B<grep>  searches  the  working
              directory.  This is equivalent to the -d recurse option.

       -R, --dereference-recursive
              Read  all  files  under each directory, recursively.  Follow all
              symbolic links, unlike -r.

   Other Options
       --line-buffered
              Use line buffering on output.   This  can  cause  a  performance
              penalty.

       -U, --binary
              Treat  the  file(s) as binary.  By default, under MS-DOS and MS-
              Windows, grep guesses whether  a  file  is  text  or  binary  as
              described  for  the  --binary-files option.  If grep decides the
              file is a text file,  it  strips  the  CR  characters  from  the
              original file contents (to make regular expressions with ^ and $
              work  correctly).   Specifying  -U  overrules  this   guesswork,
              causing  all  files  to  be  read  and  passed  to  the matching
              mechanism verbatim; if the file is a text file with CR/LF  pairs
              at   the  end  of  each  line,  this  will  cause  some  regular
              expressions to fail.  This option has  no  effect  on  platforms
              other than MS-DOS and MS-Windows.

       -z, --null-data
              Treat  input  and  output  data  as  sequences  of  lines,  each
              terminated by a zero byte (the ASCII NUL character) instead of a
              newline.   Like the -Z or --null option, this option can be used
              with commands like sort -z to process arbitrary file names.


REGULAR EXPRESSIONS

       A regular expression is a pattern that  describes  a  set  of  strings.
       Regular   expressions   are   constructed   analogously  to  arithmetic
       expressions, by using various operators to combine smaller expressions.

       grep understands three different versions of regular expression syntax:
       "basic" (BRE), "extended" (ERE) and "perl" (PCRE).  In GNU  grep  there
       is  no difference in available functionality between basic and extended
       syntaxes.  In other implementations, basic regular expressions are less
       powerful.   The  following  description  applies  to  extended  regular
       expressions; differences for basic regular expressions  are  summarized
       afterwards.    Perl-compatible   regular  expressions  give  additional
       functionality,   and   are   documented   in    B<pcresyntax>(3)    and
       B<pcrepattern>(3), but work only if PCRE support is enabled.

       The  fundamental building blocks are the regular expressions that match
       a single character.  Most characters, including all letters and digits,
       are regular expressions that match themselves.  Any meta-character with
       special meaning may be quoted by preceding it with a backslash.

       The period . matches any single character.  It is  unspecified  whether
       it matches an encoding error.

   Character Classes and Bracket Expressions
       A  bracket  expression is a list of characters enclosed by [ and ].  It
       matches any single character in that list.  If the first  character  of
       the  list is the caret ^ then it matches any character not in the list;
       it is unspecified whether it matches an encoding error.   For  example,
       the regular expression [0123456789] matches any single digit.

       Within  a  bracket  expression,  a  range  expression  consists  of two
       characters separated by a hyphen.  It matches any single character that
       sorts  between  the  two  characters,  inclusive,  using  the  locale's
       collating sequence and character set.  For example, in  the  default  C
       locale, [a-d] is equivalent to [abcd].  Many locales sort characters in
       dictionary  order,  and  in  these  locales  [a-d]  is  typically   not
       equivalent to [abcd]; it might be equivalent to [aBbCcDd], for example.
       To obtain the traditional interpretation of  bracket  expressions,  you
       can  use the C locale by setting the LC_ALL environment variable to the
       value C.

       Finally, certain named classes  of  characters  are  predefined  within
       bracket expressions, as follows.  Their names are self explanatory, and
       they  are  [:alnum:],  [:alpha:],  [:blank:],   [:cntrl:],   [:digit:],
       [:graph:],  [:lower:],  [:print:], [:punct:], [:space:], [:upper:], and
       [:xdigit:].  For example, [[:alnum:]]  means  the  character  class  of
       numbers  and  letters in the current locale.  In the C locale and ASCII
       character set encoding, this is the same as  [0-9A-Za-z].   (Note  that
       the  brackets  in these class names are part of the symbolic names, and
       must be included in addition to the  brackets  delimiting  the  bracket
       expression.)   Most  meta-characters  lose their special meaning inside
       bracket expressions.  To include a literal ]  place  it  first  in  the
       list.   Similarly,  to include a literal ^ place it anywhere but first.
       Finally, to include a literal - place it last.

   Anchoring
       The caret ^ and the dollar sign $ are meta-characters that respectively
       match the empty string at the beginning and end of a line.

   The Backslash Character and Special Expressions
       The  symbols  \<  and  \>  respectively  match  the empty string at the
       beginning and end of a word.  The symbol \b matches the empty string at
       the  edge  of a word, and \B matches the empty string provided it's not
       at the edge of a word.  The symbol \w is a synonym for [_[:alnum:]] and
       \W is a synonym for [^_[:alnum:]].

   Repetition
       A  regular  expression  may  be  followed  by one of several repetition
       operators:
       ?      The preceding item is optional and matched at most once.
       *      The preceding item will be matched zero or more times.
       +      The preceding item will be matched one or more times.
       {n}    The preceding item is matched exactly n times.
       {n,}   The preceding item is matched n or more times.
       {,m}   The preceding item is matched at most m times.  This  is  a  GNU
              extension.
       {n,m}  The  preceding  item  is  matched at least n times, but not more
              than m times.

   Concatenation
       Two regular expressions may  be  concatenated;  the  resulting  regular
       expression  matches  any  string formed by concatenating two substrings
       that respectively match the concatenated expressions.

   Alternation
       Two regular expressions may be joined by  the  infix  operator  |;  the
       resulting   regular  expression  matches  any  string  matching  either
       alternate expression.

   Precedence
       Repetition takes precedence over concatenation,  which  in  turn  takes
       precedence  over  alternation.   A  whole expression may be enclosed in
       parentheses  to  override   these   precedence   rules   and   form   a
       subexpression.

   Back-references and Subexpressions
       The back-reference \n, where n is a single digit, matches the substring
       previously matched  by  the  nth  parenthesized  subexpression  of  the
       regular expression.

   Basic vs Extended Regular Expressions
       In  basic  regular expressions the meta-characters ?, +, {, |, (, and )
       lose their special meaning; instead use the  backslashed  versions  \?,
       \+, \{, \|, \(, and \).


EXIT STATUS

       Normally the exit status is 0 if a line is selected, 1 if no lines were
       selected, and 2 if an error occurred.  However, if the -q or --quiet or
       --silent  is  used and a line is selected, the exit status is 0 even if
       an error occurred.


ENVIRONMENT

       The  behavior  of  grep  is  affected  by  the  following   environment
       variables.

       The  locale  for  category  LC_foo  is specified by examining the three
       environment variables LC_ALL, LC_foo, LANG, in that order.   The  first
       of  these  variables that is set specifies the locale.  For example, if
       LC_ALL is not set, but LC_MESSAGES is set to pt_BR, then the  Brazilian
       Portuguese  locale  is used for the LC_MESSAGES category.  The C locale
       is used if none of these environment variables are set, if  the  locale
       catalog  is  not  installed,  or if grep was not compiled with national
       language support (NLS).  The shell command locale -a lists locales that
       are currently available.

       GREP_COLOR
              This  variable  specifies  the  color  used to highlight matched
              (non-empty) text.  It is deprecated in favor of GREP_COLORS, but
              still supported.  The mt, ms, and mc capabilities of GREP_COLORS
              have priority over it.  It can only specify the  color  used  to
              highlight  the  matching  non-empty text in any matching line (a
              selected line when the -v command-line option is omitted,  or  a
              context line when -v is specified).  The default is 01;31, which
              means a bold red  foreground  text  on  the  terminal's  default
              background.

       GREP_COLORS
              Specifies  the  colors  and  other  attributes used to highlight
              various parts of the output.  Its  value  is  a  colon-separated
              list       of       capabilities      that      defaults      to
              ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36  with  the  rv
              and  ne  boolean  capabilities omitted (i.e., false).  Supported
              capabilities are as follows.

              sl=    SGR substring for whole selected  lines  (i.e.,  matching
                     lines when the -v command-line option is omitted, or non-
                     matching lines when -v is  specified).   If  however  the
                     boolean  rv capability and the -v command-line option are
                     both specified, it  applies  to  context  matching  lines
                     instead.   The  default  is  empty  (i.e., the terminal's
                     default color pair).

              cx=    SGR substring for whole context lines (i.e., non-matching
                     lines  when  the  -v  command-line  option is omitted, or
                     matching lines when -v is  specified).   If  however  the
                     boolean  rv capability and the -v command-line option are
                     both specified, it applies to selected non-matching lines
                     instead.   The  default  is  empty  (i.e., the terminal's
                     default color pair).

              rv     Boolean value that reverses (swaps) the meanings  of  the
                     sl=  and cx= capabilities when the -v command-line option
                     is specified.  The default is false (i.e., the capability
                     is omitted).

              mt=01;31
                     SGR substring for matching non-empty text in any matching
                     line (i.e., a selected  line  when  the  -v  command-line
                     option   is  omitted,  or  a  context  line  when  -v  is
                     specified).  Setting this is equivalent to  setting  both
                     ms=  and mc= at once to the same value.  The default is a
                     bold  red  text  foreground   over   the   current   line
                     background.

              ms=01;31
                     SGR  substring  for matching non-empty text in a selected
                     line.  (This is only used when the -v command-line option
                     is  omitted.)   The  effect  of  the  sl=  (or cx= if rv)
                     capability  remains  active  when  this  kicks  in.   The
                     default  is  a  bold red text foreground over the current
                     line background.

              mc=01;31
                     SGR substring for matching non-empty text  in  a  context
                     line.  (This is only used when the -v command-line option
                     is specified.)  The effect of the  cx=  (or  sl=  if  rv)
                     capability  remains  active  when  this  kicks  in.   The
                     default is a bold red text foreground  over  the  current
                     line background.

              fn=35  SGR  substring for file names prefixing any content line.
                     The  default  is  a  magenta  text  foreground  over  the
                     terminal's default background.

              ln=32  SGR  substring  for  line  numbers  prefixing any content
                     line.  The default is a green text  foreground  over  the
                     terminal's default background.

              bn=32  SGR  substring  for  byte  offsets  prefixing any content
                     line.  The default is a green text  foreground  over  the
                     terminal's default background.

              se=36  SGR  substring  for  separators that are inserted between
                     selected line fields (:), between  context  line  fields,
                     (-),  and  between  groups of adjacent lines when nonzero
                     context is specified (--).  The default is  a  cyan  text
                     foreground over the terminal's default background.

              ne     Boolean  value  that prevents clearing to the end of line
                     using Erase in Line (EL) to Right  (\33[K)  each  time  a
                     colorized  item  ends.   This  is  needed on terminals on
                     which EL is not supported.  It  is  otherwise  useful  on
                     terminals  for  which  the back_color_erase (bce) boolean
                     terminfo capability  does  not  apply,  when  the  chosen
                     highlight colors do not affect the background, or when EL
                     is too slow or causes too much flicker.  The  default  is
                     false (i.e., the capability is omitted).

              Note  that  boolean  capabilities  have  no =... part.  They are
              omitted (i.e., false) by default and become true when specified.

              See   the   Select   Graphic  Rendition  (SGR)  section  in  the
              documentation of the text terminal that is  used  for  permitted
              values   and  their  meaning  as  character  attributes.   These
              substring values are integers in decimal representation and  can
              be  concatenated with semicolons.  grep takes care of assembling
              the result into a  complete  SGR  sequence  (\33[...m).   Common
              values to concatenate include 1 for bold, 4 for underline, 5 for
              blink, 7 for inverse, 39 for default foreground color, 30 to  37
              for  foreground  colors,  90  to 97 for 16-color mode foreground
              colors, 38;5;0 to 38;5;255  for  88-color  and  256-color  modes
              foreground colors, 49 for default background color, 40 to 47 for
              background colors, 100  to  107  for  16-color  mode  background
              colors,  and 48;5;0 to 48;5;255 for 88-color and 256-color modes
              background colors.

       LC_ALL, LC_COLLATE, LANG
              These variables specify the locale for the LC_COLLATE  category,
              which  determines the collating sequence used to interpret range
              expressions like [a-z].

       LC_ALL, LC_CTYPE, LANG
              These variables specify the locale for  the  LC_CTYPE  category,
              which  determines the type of characters, e.g., which characters
              are whitespace.  This category  also  determines  the  character
              encoding,  that  is, whether text is encoded in UTF-8, ASCII, or
              some other encoding.  In the C or POSIX locale,  all  characters
              are  encoded  as  a  single  byte  and  every  byte  is  a valid
              character.

       LC_ALL, LC_MESSAGES, LANG
              These variables specify the locale for the LC_MESSAGES category,
              which  determines the language that grep uses for messages.  The
              default C locale uses American English messages.

       POSIXLY_CORRECT
              If set, grep behaves as POSIX requires; otherwise, grep  behaves
              more  like other GNU programs.  POSIX requires that options that
              follow file names must be treated as  file  names;  by  default,
              such  options  are permuted to the front of the operand list and
              are treated as options.  Also, POSIX requires that  unrecognized
              options be diagnosed as "illegal", but since they are not really
              against the law the default is to diagnose  them  as  "invalid".
              POSIXLY_CORRECT   also   disables  _N_GNU_nonoption_argv_flags_,
              described below.

       _N_GNU_nonoption_argv_flags_
              (Here N is grep's numeric process ID.)  If the ith character  of
              this  environment variable's value is 1, do not consider the ith
              operand of grep to be an option, even if it appears to  be  one.
              A  shell  can  put  this  variable  in  the environment for each
              command it runs, specifying which operands are  the  results  of
              file name wildcard expansion and therefore should not be treated
              as options.  This behavior is available  only  with  the  GNU  C
              library, and only when POSIXLY_CORRECT is not set.


NOTES

       This  man  page  is maintained only fitfully; the full documentation is
       often more up-to-date.


COPYRIGHT

       Copyright 1998-2000, 2002, 2005-2021 Free Software Foundation, Inc.

       This is free software; see the source for copying conditions.  There is
       NO  warranty;  not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.


BUGS

   Reporting Bugs
       Email bug reports to the bug-reporting address <bug-grep@gnu.org>.   An
       email  archive  <https://lists.gnu.org/mailman/listinfo/bug-grep> and a
       bug  tracker   <https://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep>
       are available.

   Known Bugs
       Large  repetition  counts  in the {n,m} construct may cause grep to use
       lots of memory.  In addition, certain other obscure regular expressions
       require  exponential  time  and space, and may cause grep to run out of
       memory.

       Back-references are very slow, and may require exponential time.


EXAMPLE

       The following example outputs the location and  contents  of  any  line
       containing  "f"  and  ending  in  ".c", within all files in the current
       directory whose names contain "g" and end in ".h".  The -n option  out-
       puts  line numbers, the -- argument treats expansions of "*g*.h" start-
       ing with "-" as file names not options, and the  empty  file  /dev/null
       causes file names to be output even if only one file name happens to be
       of the form "*g*.h".

         $ grep -n -- 'f.*\.c$' *g*.h  /dev/null  argmatch.h:1:/*  definitions
         and prototypes for argmatch.c

       The only line that matches is line 1 of argmatch.h.  Note that the reg-
       ular expression syntax used in the pattern differs  from  the  globbing
       syntax that the shell uses to match file names.


SEE ALSO

   Regular Manual Pages
       awk(1),  cmp(1),  diff(1), find(1), perl(1), sed(1), sort(1), xargs(1),
       read(2), pcre(3), pcresyntax(3), pcrepattern(3), terminfo(5),  glob(7),
       regex(7)

   Full Documentation
       A complete manual <https://www.gnu.org/software/grep/manual/> is avail-
       able.  If the info and grep programs are  properly  installed  at  your
       site, the command

              info grep

       should give you access to the complete manual.



GNU grep 3.7                      2019-12-29                           grep(1)

grep 3.7 - Generated Mon Aug 16 13:12:57 CDT 2021
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