grep(1)



GREP(1)                          User Commands                         GREP(1)

NAME
       grep, egrep, fgrep, rgrep - 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 patterns
       separated by newline characters, and grep prints each line that matches
       a pattern.

       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, fgrep and rgrep are the same
       as grep -E, grep -F, and grep -r,  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.

   Matcher Selection
       -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   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, so that characters that differ only in
              case match 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.  The
              scanning will stop on the first match.

       -l, --files-with-matches
              Suppress normal output; instead print the  name  of  each  input
              file  from  which  output would normally have been printed.  The
              scanning will stop on the 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.

       -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  is  especially  useful   when
              implementing  tools  like  zgrep,  e.g.,  gzip -cd foo.gz | grep
              --label=foo -H something.  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.

       -u, --unix-byte-offsets
              Report  Unix-style  byte  offsets.   This  switch causes grep to
              report byte offsets as if the file were a Unix-style text  file,
              i.e.,  with  CR  characters  stripped  off.   This  will produce
              results identical to running  grep  on  a  Unix  machine.   This
              option  has  no  effect unless -b option is also used; it has no
              effect on platforms other than MS-DOS and MS-Windows.

       -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.

   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 when grep discovers that a file
              is binary it suppresses any further output, and instead  outputs
              either  a one-line message saying that a binary file matches, or
              no message if there is no match.

              If TYPE is without-match, when grep discovers  that  a  file  is
              binary 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 any suffix starting after a / and before a
              non-/.  When searching recursively, skip any subfile whose  base
              name  matches  GLOB; the base name is the part after the last /.
              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).

       -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,  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 pcresyntax(3) and pcrepattern(3),
       but work only if PCRE is available in the system.

       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:],  [: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 \?,
       \+, \{, \|, \(, and \).

ENVIRONMENT VARIABLES
       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_OPTIONS
              This variable specifies default options to be placed in front of
              any explicit options.  As  this  causes  problems  when  writing
              portable  scripts,  this  feature  will  be  removed in a future
              release of grep, and grep warns if it is used.   Please  use  an
              alias or script instead.

       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.

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.

COPYRIGHT
       Copyright 1998-2000, 2002, 2005-2018 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.

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

   POSIX Programmer's Manual Page
       grep(1p).

   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.

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

GNU grep 3.3                      2018-05-11                           GREP(1)

Man(1) output converted with man2html
list of all man pages