1 .TH GREP 1
2 .SH NAME
3 grep \- search a file for a pattern
4 .SH SYNOPSIS
5 .B grep
6 [
7 .I option ...
8 ]
9 .I pattern
10 [
11 .I file ...
12 ]
13 .SH DESCRIPTION
14 .I Grep\^
15 searches the input
16 .I files\^
17 (standard input default)
18 for lines that match the
19 .IR pattern ,
20 a regular expression as defined in
21 .IR regexp (6)
22 with the addition of a newline character as an alternative
23 (substitute for
24 .BR | )
25 with lowest precedence.
26 Normally, each line matching the pattern is `selected',
27 and each selected line is copied to the standard output.
28 The options are
29 .TP
30 .B -c
31 Print only a count of matching lines.
32 .PD 0
33 .TP
34 .B -h
35 Do not print file name tags (headers) with output lines.
36 .TP
37 .B -e
38 The following argument is taken as a
39 .IR pattern .
40 This option makes it easy to specify patterns that
41 might confuse argument parsing, such as
42 .BR -n .
43 .TP
44 .B -i
45 Ignore alphabetic case distinctions.  The implementation
46 folds into lower case all letters in the pattern and input before
47 interpretation.  Matched lines are printed in their original form.
48 .TP
49 .B -l
50 (ell) Print the names of files with selected lines; don't print the lines.
51 .TP
52 .B -L
53 Print the names of files with no selected lines;
54 the converse of
55 .BR -l .
56 .TP
57 .B -n
58 Mark each printed line with its line number counted in its file.
59 .TP
60 .B -s
61 Produce no output, but return status.
62 .TP
63 .B -v
64 Reverse: print lines that do not match the pattern.
65 .TP
66 .B -f
67 The pattern argument is the name of a file containing regular
68 expressions one per line.
69 .TP
70 .B -b
71 Don't buffer the output: write each output line as soon as it is discovered.
72 .PD
73 .PP
74 Output lines are tagged by file name when there is more than one
75 input file.
76 (To force this tagging, include
77 .B /dev/null
78 as a file name argument.)
79 .PP
80 Care should be taken when
81 using the shell metacharacters
82 .B $*[^|()=\e
83 and newline
84 in
85 .IR pattern ;
86 it is safest to enclose the
87 entire expression
88 in single quotes
89 .BR \&\|' \|.\|.\|.\| ' .
90 An expression starting with '*'
91 will treat the rest of the expression
92 as literal characters.
93 .SH SOURCE
94 .B /usr/local/plan9/src/cmd/grep
95 .SH SEE ALSO
96 .IR ed (1),
97 .IR awk (1),
98 .IR sed (1),
99 .IR sam (1),
100 .IR regexp (6)
101 .SH DIAGNOSTICS
102 Exit status is null if any lines are selected,
103 or non-null when no lines are selected or an error occurs.