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\input texinfo  @c -*-texinfo-*-
@c %**start of header
@setfilename grep.info
@settitle grep, print lines matching a pattern
@c %**end of header

@c This file has the new style title page commands.
@c Run `makeinfo' rather than `texinfo-format-buffer'.

@c smallbook

@c tex
@c \overfullrule=0pt
@c end tex

@include version.texi

@c Combine indices.
@syncodeindex ky cp
@syncodeindex pg cp
@syncodeindex tp cp

@defcodeindex op
@syncodeindex op fn
@syncodeindex vr fn

@ifinfo
@direntry
* grep: (grep).                   print lines matching a pattern.
@end direntry
This file documents @command{grep}, a pattern matching engine.


Published by the Free Software Foundation,
59 Temple Place - Suite 330
Boston, MA 02111-1307, USA

@c man begin COPYRIGHT
Copyright @copyright{} 2000, 2001 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through TeX and print the
results, provided the printed document carries a copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``GNU General Public License'' and ``GNU Free
Documentation License'', with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the section
entitled ``GNU Free Documentation License'' (@pxref{Copying}).
@c man end
@end ifinfo

@setchapternewpage off

@titlepage
@title grep, searching for a pattern
@subtitle version @value{VERSION}, @value{UPDATED}
@author Alain Magloire et al.

@page
@vskip 0pt plus 1filll
Copyright @copyright{} 2000, 2001 Free Software Foundation, Inc.

@sp 2
Published by the Free Software Foundation, @*
59 Temple Place - Suite 330, @*
Boston, MA 02111-1307, USA

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``GNU General Public License'' and ``GNU Free
Documentation License'', with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the section
entitled ``GNU Free Documentation License''.
@end titlepage


@ifnottex
@node Top
@top Grep

@command{grep} searches for lines matching a pattern.

This document was produced for version @value{VERSION} of @sc{gnu}
@command{grep}.
@end ifnottex

@menu
* Introduction::                Introduction.
* Invoking::                    Invoking @command{grep}; description of options.
* Diagnostics::                 Exit status returned by @command{grep}.
* Grep Programs::               @command{grep} programs.
* Regular Expressions::         Regular Expressions.
* Usage::                       Examples.
* Reporting Bugs::              Reporting Bugs.
* Copying::                     License terms.
* Concept Index::               A menu with all the topics in this manual.
* Index::                       A menu with all @command{grep} commands
                                 and command-line options.
@end menu


@node Introduction, Invoking, Top, Top
@chapter Introduction

@cindex Searching for a pattern.

@command{grep} searches the input files
for lines containing a match to a given
pattern list.  When it finds a match in a line, it copies the line to standard
output (by default), or does whatever other sort of output you have requested
with options.

Though @command{grep} expects to do the matching on text,
it has no limits on input line length other than available memory,
and it can match arbitrary characters within a line.
If the final byte of an input file is not a newline,
@command{grep} silently supplies one.
Since newline is also a separator for the list of patterns, there
is no way to match newline characters in a text.

@node Invoking
@chapter Invoking @command{grep}

@command{grep} comes with a rich set of options from @sc{posix.2} and @sc{gnu}
extensions.

@table @samp

@item -c
@itemx --count
@opindex -c
@opindex --count
@cindex counting lines
Suppress normal output; instead print a count of matching
lines for each input file.  With the @samp{-v}, @samp{--invert-match} option,
count non-matching lines.

@item -e @var{pattern}
@itemx --regexp=@var{pattern}
@opindex -e
@opindex --regexp=@var{pattern}
@cindex pattern list
Use @var{pattern} as the pattern; useful to protect patterns
beginning with a @samp{-}.

@item -f @var{file}
@itemx --file=@var{file}
@opindex -f
@opindex --file
@cindex pattern from file
Obtain patterns from @var{file}, one per line.  The empty
file contains zero patterns, and therefore matches nothing.

@item -i
@itemx --ignore-case
@opindex -i
@opindex --ignore-case
@cindex case insensitive search
Ignore case distinctions in both the pattern and the input files.

@item -l
@itemx --files-with-matches
@opindex -l
@opindex --files-with-matches
@cindex names of matching files
Suppress normal output; instead print the name of each input
file from which output would normally have been printed.
The scanning of every file will stop on the first match.

@item -n
@itemx --line-number
@opindex -n
@opindex --line-number
@cindex line numbering
Prefix each line of output with the line number within its input file.

@item -o
@itemx --only-matching
@opindex -o
@opindex --only-matching
@cindex only matching
Print only the part of matching lines that actually matches @var{pattern}.

@item -q
@itemx --quiet
@itemx --silent
@opindex -q
@opindex --quiet
@opindex --silent
@cindex 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 @samp{-s} or @samp{--no-messages} option.

@item -s
@itemx --no-messages
@opindex -s
@opindex --no-messages
@cindex suppress error messages
Suppress error messages about nonexistent or unreadable files.
Portability note: unlike @sc{gnu} @command{grep}, traditional
@command{grep} did not conform to @sc{posix.2}, because traditional
@command{grep} lacked a @samp{-q} option and its @samp{-s} option behaved
like @sc{gnu} @command{grep}'s @samp{-q} option.  Shell scripts intended
to be portable to traditional @command{grep} should avoid both
@samp{-q} and @samp{-s} and should redirect
output to @file{/dev/null} instead.

@item -v
@itemx --invert-match
@opindex -v
@opindex --invert-match
@cindex invert matching
@cindex print non-matching lines
Invert the sense of matching, to select non-matching lines.

@item -x
@itemx --line-regexp
@opindex -x
@opindex --line-regexp
@cindex match the whole line
Select only those matches that exactly match the whole line.

@end table

@section @sc{gnu} Extensions

@table @samp

@item -A @var{num}
@itemx --after-context=@var{num}
@opindex -A
@opindex --after-context
@cindex after context
@cindex context lines, after match
Print @var{num} lines of trailing context after matching lines.

@item -B @var{num}
@itemx --before-context=@var{num}
@opindex -B
@opindex --before-context
@cindex before context
@cindex context lines, before match
Print @var{num} lines of leading context before matching lines.

@item -C @var{num}
@itemx --context=@var{num}
@opindex -C
@opindex --context
@cindex context
Print @var{num} lines of output context.

@item --colour[=@var{WHEN}]
@itemx --color[=@var{WHEN}]
@opindex --colour
@cindex highlight, color, colour
The matching string is surrounded by the marker specify in @var{GREP_COLOR}.
@var{WHEN} may be `never', `always', or `auto'.

@item -@var{num}
@opindex -NUM
Same as @samp{--context=@var{num}} lines of leading and trailing
context.  However, grep will never print any given line more than once.


@item -V
@itemx --version
@opindex -V
@opindex --version
@cindex Version, printing
Print the version number of @command{grep} to the standard output stream.
This version number should be included in all bug reports.

@item --help
@opindex --help
@cindex Usage summary, printing
Print a usage message briefly summarizing these command-line options
and the bug-reporting address, then exit.

@itemx --binary-files=@var{type}
@opindex --binary-files
@cindex binary files
If the first few bytes of a file indicate that the file contains binary
data, assume that the file is of type @var{type}.  By default,
@var{type} is @samp{binary}, and @command{grep} normally outputs either
a one-line message saying that a binary file matches, or no message if
there is no match.  If @var{type} is @samp{without-match},
@command{grep} assumes that a binary file does not match;
this is equivalent to the @samp{-I} option.  If @var{type}
is @samp{text}, @command{grep} processes a binary file as if it were
text; this is equivalent to the @samp{-a} option.
@emph{Warning:} @samp{--binary-files=text} 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.

@item -b
@itemx --byte-offset
@opindex -b
@opindex --byte-offset
@cindex byte offset
Print the byte offset within the input file before each line of output.
When @command{grep} runs on @sc{ms-dos} or MS-Windows, the printed
byte offsets
depend on whether the @samp{-u} (@samp{--unix-byte-offsets}) option is
used; see below.

@item -D @var{action}
@itemx --devices=@var{action}
@opindex -D
@opindex --devices
@cindex device search
If an input file is a device, FIFO or socket, use @var{action} to process it.
By default, @var{action} is @samp{read}, which means that devices are
read just as if they were ordinary files.
If @var{action} is @samp{skip}, devices, FIFOs and sockets are silently
skipped.

@item -d @var{action}
@itemx --directories=@var{action}
@opindex -d
@opindex --directories
@cindex directory search
If an input file is a directory, use @var{action} to process it.
By default, @var{action} is @samp{read}, which means that directories are
read just as if they were ordinary files (some operating systems
and filesystems disallow this, and will cause @command{grep} to print error
messages for every directory or silently skip them). If @var{action} is
@samp{skip}, directories are silently skipped.  If @var{action} is
@samp{recurse}, @command{grep} reads all files under each directory,
recursively; this is equivalent to the @samp{-r} option.

@item -H
@itemx --with-filename
@opindex -H
@opindex --With-filename
@cindex with filename prefix
Print the filename for each match.

@item -h
@itemx --no-filename
@opindex -h
@opindex --no-filename
@cindex no filename prefix
Suppress the prefixing of filenames on output when multiple files are searched.

@item --line-buffered
@opindex --line-buffered
@cindex line buffering
Set the line buffering policy, this can be a performance penality.

@item --label=@var{LABEL}
@opindex --label