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|
.TH GRE 1
.CT 1 files
.SH NAME
gre, grep, egrep, fgrep \(mi search a file for a pattern
.SH SYNOPSIS
.B gre
[
.I option ...
]
.I pattern
[
.I file ...
]
.PP
.B grep
[
.I option ...
]
.I pattern
[
.I file ...
]
.PP
.B egrep
[
.I option ...
]
.I pattern
[
.I file ...
]
.PP
.B fgrep
[
.I option ...
]
.I strings
[
.I file ...
]
.SH DESCRIPTION
.I Gre\^
searches the input
.I files\^
(standard input default)
for lines (with newlines excluded) that match the
.I pattern,
a regular expression as defined in
.IR re (3).
A file name of
.B -
is interpreted as standard input.
Normally, each line matching the pattern is `selected',
and each selected line is copied to the standard output.
The options are
.TP
.B -1
Print only the first selected line of each file argument.
.PD 0
.TP
.B -b
Mark each printed line with its byte position in its file.
This is sometimes useful in locating patterns in non-text files.
.TP
.B -c
Print only a count of matching lines.
.TP
.BI -e " pattern"
Same as a simple
.I pattern
argument,
but useful when
.I pattern
begins with a
.BR - .
.TP
.B -E
Simulate
.IR egrep.
.TP
.BI -f " file"
Read the pattern from
.IR file ;
there is no
.I pattern
argument
.TP
.B -F
Simulate
.IR fgrep.
.TP
.B -G
Simulate
.IR grep.
.TP
.B -h
Do not print filename tags (headers) with output lines.
.TP
.B -i
Ignore alphabetic case distinctions.
.TP
.B -l
Print the names of files with selected lines; don't print the lines.
.TP
.B -L
Print the names of files with no selected lines;
the converse of
.BR -l .
.TP
.B -n
Mark each printed line with its line number counted in its file.
.TP
.B -s
Produce no output, but return status.
.TP
.B -v
Reverse: print lines that do not match the pattern.
.TP
.B -x
Exact match: The pattern is
.BI ^( pattern )$ .
The implicit parentheses count in back references.
.PD
.PP
Output lines are tagged by filename when there is more than one
input file.
(To force this tagging, include
.B /dev/null
as a filename argument.)
If the output line exceeds some internal limit,
a warning is given and a small block of text surrounding the match is printed.
.PP
Care should be taken when
using the shell metacharacters
.B $*[^|()\e
and newline
in
.IR pattern ;
it is safest to enclose the
entire expression
in single quotes
.BR \&\|\(fm \|.\|.\|.\| \(fm .
.PP
.I Gre
supplants three classic programs, which are still available:
.PP
.I Grep
handles only
.IR ed (1)-like
regular expressions.
It uses
.L \e(\|\e)
instead of
.LR (\|) .
.PP
.I Egrep
handles the same patterns as
.I gre
except for back-referencing with
.BR \e1 ,
.BR \e2 ,
\&...
.PP
.I Fgrep
handles no operators except newline (alternation).
.SH SEE ALSO
.IR re (3),
.IR awk (1),
.IR sed (1),
.IR sam (9.1),
.IR strings (1)
.SH DIAGNOSTICS
Exit status is 0 if any lines are selected,
1 if none, 2 for syntax errors, inaccessible files
(even if matches were found).
Warnings will be given for input lines that exceed
a (generous) internal limit.
.SH BUGS
.I Grep, egrep,
and
.I fgrep
do not support some options and print block numbers
rather than byte numbers for option
.BR -b .
.br
.I Egrep
may fail on input containing characters greater
than 0176.
|
