grep.1

linux平台中

.\" grep man page
.if !\n(.g \{\
.	if !\w|\*(lq| \{\
.		ds lq ``
.		if \w'\(lq' .ds lq "\(lq
.	\}
.	if !\w|\*(rq| \{\
.		ds rq ''
.		if \w'\(rq' .ds rq "\(rq
.	\}
.\}
.de Id
.ds Dt \\$4
..
.Id $Id: grep.1,v 1.23 2002/01/22 13:20:04 bero Exp $
.TH GREP 1 \*(Dt "GNU Project"
.SH NAME
grep, egrep, fgrep \- print lines matching a pattern
.SH SYNOPSIS
.B grep
.RI [ options ]
.I PATTERN
.RI [ FILE .\|.\|.]
.br
.B grep
.RI [ options ]
.RB [ \-e
.I PATTERN
|
.B \-f
.IR FILE ]
.RI [ FILE .\|.\|.]
.SH DESCRIPTION
.PP
.B Grep
searches the named input
.IR FILE s
(or standard input if no files are named, or
the file name
.B \-
is given)
for lines containing a match to the given
.IR PATTERN .
By default,
.B grep
prints the matching lines.
.PP
In addition, two variant programs
.B egrep
and
.B fgrep
are available.
.B Egrep
is the same as
.BR "grep\ \-E" .
.B Fgrep
is the same as
.BR "grep\ \-F" .
.SH OPTIONS
.TP
.BI \-A " NUM" "\fR,\fP \-\^\-after-context=" NUM
Print
.I NUM
lines of trailing context after matching lines.
Places a line containing
.B \-\^\-
between contiguous groups of matches.
.TP
.BR \-a ", " \-\^\-text
Process a binary file as if it were text; this is equivalent to the
.B \-\^\-binary-files=text
option.
.TP
.BI \-B " NUM" "\fR,\fP \-\^\-before-context=" NUM
Print
.I NUM
lines of leading context before matching lines.
Places a line containing
.B \-\^\-
between contiguous groups of matches.
.TP
.BI \-C " NUM" "\fR,\fP \-\^\-context=" NUM
Print
.I NUM
lines of output context.
Places a line containing
.B \-\^\-
between contiguous groups of matches.
.TP
.BR \-b ", " \-\^\-byte-offset
Print the byte offset within the input file before
each line of output.
.TP
.BI \-\^\-binary-files= TYPE
If the first few bytes of a file indicate that the file contains binary
data, assume that the file is of type
.IR TYPE .
By default,
.I TYPE
is
.BR binary ,
and
.B grep
normally outputs either
a one-line message saying that a binary file matches, or no message if
there is no match.
If
.I TYPE
is
.BR without-match ,
.B grep
assumes that a binary file does not match; this is equivalent to the
.B \-I
option.
If
.I TYPE
is
.BR text ,
.B grep
processes a binary file as if it were text; this is equivalent to the
.B \-a
option.
.I Warning:
.B "grep \-\^\-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.
.TP
.BI \-\^\-colour[=\fIWHEN\fR] ", " \-\^\-color[=\fIWHEN\fR]
Surround the matching string with the marker find in
.B GREP_COLOR
environment variable. WHEN may be `never', `always', or `auto'
.TP
.BR \-c ", " \-\^\-count
Suppress normal output; instead print a count of
matching lines for each input file.
With the
.BR \-v ", " \-\^\-invert-match
option (see below), count non-matching lines.
.TP
.BI \-D " ACTION" "\fR,\fP \-\^\-devices=" ACTION
If an input file is a device, FIFO or socket, use
.I ACTION
to process it.  By default,
.I ACTION
is
.BR read ,
which means that devices are read just as if they were ordinary files.
If
.I ACTION
is
.BR skip ,
devices are silently skipped.
.TP
.BI \-d " ACTION" "\fR,\fP \-\^\-directories=" ACTION
If an input file is a directory, use
.I ACTION
to process it.  By default,
.I ACTION
is
.BR read ,
which means that directories are read just as if they were ordinary files.
If
.I ACTION
is
.BR skip ,
directories are silently skipped.
If
.I ACTION
is
.BR recurse ,
.B grep
reads all files under each directory, recursively;
this is equivalent to the
.B \-r
option.
.TP
.BR \-E ", " \-\^\-extended-regexp
Interpret
.I PATTERN
as an extended regular expression (see below).
.TP
.BI \-e " PATTERN" "\fR,\fP \-\^\-regexp=" PATTERN
Use
.I PATTERN
as the pattern; useful to protect patterns beginning with
.BR \- .
.TP
.BR \-F ", " \-\^\-fixed-strings
Interpret
.I PATTERN
as a list of fixed strings, separated by newlines,
any of which is to be matched.
.BR \-P ", " \-\^\-perl-regexp
Interpret
.I PATTERN
as a Perl regular expression.
.TP
.BI \-f " FILE" "\fR,\fP \-\^\-file=" FILE
Obtain patterns from
.IR FILE ,
one per line.
The empty file contains zero patterns, and therefore matches nothing.
.TP
.BR \-G ", " \-\^\-basic-regexp
Interpret
.I PATTERN
as a basic regular expression (see below).  This is the default.
.TP
.BR \-H ", " \-\^\-with-filename
Print the filename for each match.
.TP
.BR \-h ", " \-\^\-no-filename
Suppress the prefixing of filenames on output
when multiple files are searched.
.TP
.B \-\^\-help
Output a brief help message.
.TP
.BR \-I
Process a binary file as if it did not contain matching data; this is
equivalent to the
.B \-\^\-binary-files=without-match
option.
.TP
.BR \-i ", " \-\^\-ignore-case
Ignore case distinctions in both the
.I PATTERN
and the input files.
.TP
.BR \-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.
.TP
.BR \-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.
.TP
.BI \-m " NUM" "\fR,\fP \-\^\-max-count=" NUM
Stop reading a file after
.I NUM
matching lines.  If the input is standard input from a regular file,
and
.I NUM
matching lines are output,
.B 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
.B grep
stops after
.I NUM
matching lines, it outputs any trailing context lines.  When the
.B \-c
or
.B \-\^\-count
option is also used,
.B grep
does not output a count greater than
.IR NUM .
When the
.B \-v
or
.B \-\^\-invert-match
option is also used,
.B grep
stops after outputting
.I NUM
non-matching lines.
.TP
.B \-\^\-mmap
If possible, use the
.BR mmap (2)
system call to read input, instead of
the default
.BR read (2)
system call.  In some situations,
.B \-\^\-mmap
yields better performance.  However,
.B \-\^\-mmap
can cause undefined behavior (including core dumps)
if an input file shrinks while
.B grep
is operating, or if an I/O error occurs.
.TP
.BR \-n ", " \-\^\-line-number
Prefix each line of output with the line number
within its input file.
.TP
.BR \-o ", " \-\^\-only-matching
Show only the part of a matching line that matches
.I PATTERN.
.TP
.BI \-\^\-label= LABEL
Displays input actually coming from standard input as input coming from file
.I LABEL.
This is especially useful for tools like zgrep, e.g.
.B "gzip -cd foo.gz |grep --label=foo something"
.TP
.BR \-\^\-line-buffering
Use line buffering, it can be a performance penality.
.TP
.BR \-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
.B \-s
or
.B \-\^\-no-messages
option.
.TP
.BR \-R ", " \-r ", " \-\^\-recursive
Read all files under each directory, recursively;
this is equivalent to the
.B "\-d recurse"
option.
.TP
.BR "\fR \fP \-\^\-include=" PATTERN
Recurse in directories only searching file matching
.I PATTERN.
.TP
.BR "\fR \fP \-\^\-exclude=" PATTERN
Recurse in directories skip file matching
.I PATTERN.
.TP
.BR \-s ", " \-\^\-no-messages
Suppress error messages about nonexistent or unreadable files.
Portability note: unlike \s-1GNU\s0
.BR grep ,
traditional
.B grep
did not conform to \s-1POSIX.2\s0, because traditional
.B grep
lacked a
.B \-q
option and its
.B \-s
option behaved like \s-1GNU\s0
.BR grep 's
.B \-q
option.
Shell scripts intended to be portable to traditional
.B grep
should avoid both
.B \-q
and
.B \-s
and should redirect output to /dev/null instead.
.TP
.BR \-U ", " \-\^\-binary
Treat the file(s) as binary.  By default, under MS-DOS and MS-Windows,
.BR grep
guesses the file type by looking at the contents of the first 32KB
read from the file.  If
.BR grep
decides the file is a text file, it strips the CR characters from the
original file contents (to make regular expressions with
.B ^
and
.B $
work correctly).  Specifying
.B \-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.
.TP
.BR \-u ", " \-\^\-unix-byte-offsets
Report Unix-style byte offsets.  This switch causes
.B grep
to report byte offsets as if the file were Unix-style text file, i.e. with
CR characters stripped off.  This will produce results identical to running
.B grep
on a Unix machine.  This option has no effect unless
.B \-b
option is also used;
it has no effect on platforms other than MS-DOS and MS-Windows.
.TP
.BR \-V ", " \-\^\-version
Print the version number of
.B grep
to standard error.  This version number should
be included in all bug reports (see below).
.TP