Provided by: grep_3.3-1build1_amd64 bug

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 available.  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.