[unix-history] / usr / man / man1 / grep.1

.TH GREP 1 
.SH NAME
grep, egrep, fgrep \- search a file for a pattern
.SH SYNOPSIS
.B grep
[ option ] ...
expression [ file ] ...
.LP
.B egrep 
[ option ] ...
[ expression ]
[ file ] ...
.PP
.B fgrep
[ option ] ...
[ strings ]
[ file ]
.SH DESCRIPTION
Commands of the
.I grep
family search the input
.I files
(standard input default)
for lines matching
a pattern.
Normally, each line found
is copied to the standard output.
.I Grep
patterns are limited regular expressions in the style of
.IR ed (1);
it uses a compact nondeterministic algorithm.
.I Egrep
patterns are full regular expressions;
it uses a fast deterministic algorithm that
sometimes needs exponential space.
.I Fgrep
patterns are fixed strings; it is fast and compact.
The following options are recognized.
.TP
.B \-v
All lines but those matching
are printed.
.TP
.B \-x
(Exact) only lines matched in their entirety are printed
.RI ( fgrep
only).
.TP
.B \-c
Only a count of matching lines is printed.
.TP
.B \-l
The names of files with matching lines are listed (once)
separated by newlines.
.TP
.B \-n
Each line is preceded by
its relative line number in the file.
.TP
.B \-b
Each line is preceded by the block number
on which it was found.
This is sometimes useful in locating
disk block numbers by context.
.TP
.BI \-e " expression"
Same as a simple
.I expression 
argument,
but useful when the
.I expression
begins with a \-.
.TP
.BI \-f " file"
The regular expression
.RI ( egrep )
or string list
.RI ( fgrep ) 
is taken from the
.I file.
.PP
In all cases the file name is shown if there is more than one input file.
Care should be taken when
using the characters
$ * [ ^ | ( ) and \\ in the
.I expression
as they are
also meaningful to the Shell.
It is safest to enclose the
entire
.I expression
argument in single quotes \' \'.
.PP
.I Fgrep
searches for lines that contain one of the (newline-separated)
.I strings.
.PP
.I Egrep
accepts extended regular expressions.
In the following description `character' excludes
newline:
.IP
A \e followed by a single character
other than newline
matches that character.
.IP
The character ^ ($) matches the beginning (end) of
a line.
.IP
A 
.B .
matches any character.
.IP
A single character not otherwise endowed with special
meaning matches that character.
.IP
A string enclosed in brackets [\|]
matches any single character from the string.
Ranges of ASCII character codes may be abbreviated
as in `a\-z0\-9'.
A ]
may occur only as the first character of the string.
A literal \- must be placed where it can't be
mistaken as a range indicator.
.IP
A regular expression followed by * (+, ?) matches a sequence
of 0 or more (1 or more, 0 or 1)
matches of the regular expression.
.IP
Two regular expressions concatenated
match a match of the first followed by a match of 
the second.
.IP
Two regular expressions separated by | or newline
match either a match for the first or a match for the
second.
.IP
A regular expression enclosed in parentheses
matches a match for the regular expression.
.LP
The order of precedence of operators
at the same parenthesis level
is [\|] then
*+? then concatenation then | and newline.
.SH "SEE ALSO"
ed(1),
sed(1),
sh(1)
.SH DIAGNOSTICS
Exit status is 0 if any matches are found,
1 if none, 2 for syntax errors or inaccessible files.
.SH BUGS
Ideally there should be only one
.I grep,
but we don't know a single algorithm that spans a wide enough
range of space-time tradeoffs.
.PP
Lines
are limited to 256 characters;
longer lines are truncated.
Commit	Line	Data
59182018 TL	1	.TH GREP 1
	2	.SH NAME
	3	grep, egrep, fgrep \- search a file for a pattern
	4	.SH SYNOPSIS
	5	.B grep
	6	[ option ] ...
	7	expression [ file ] ...
	8	.LP
	9	.B egrep
	10	[ option ] ...
	11	[ expression ]
	12	[ file ] ...
	13	.PP
	14	.B fgrep
	15	[ option ] ...
	16	[ strings ]
	17	[ file ]
	18	.SH DESCRIPTION
	19	Commands of the
	20	.I grep
	21	family search the input
	22	.I files
	23	(standard input default)
	24	for lines matching
	25	a pattern.
	26	Normally, each line found
	27	is copied to the standard output.
	28	.I Grep
	29	patterns are limited regular expressions in the style of
	30	.IR ed (1);
	31	it uses a compact nondeterministic algorithm.
	32	.I Egrep
	33	patterns are full regular expressions;
	34	it uses a fast deterministic algorithm that
	35	sometimes needs exponential space.
	36	.I Fgrep
	37	patterns are fixed strings; it is fast and compact.
	38	The following options are recognized.
	39	.TP
	40	.B \-v
	41	All lines but those matching
	42	are printed.
	43	.TP
	44	.B \-x
	45	(Exact) only lines matched in their entirety are printed
	46	.RI ( fgrep
	47	only).
	48	.TP
	49	.B \-c
	50	Only a count of matching lines is printed.
	51	.TP
	52	.B \-l
	53	The names of files with matching lines are listed (once)
	54	separated by newlines.
	55	.TP
	56	.B \-n
	57	Each line is preceded by
	58	its relative line number in the file.
	59	.TP
	60	.B \-b
	61	Each line is preceded by the block number
	62	on which it was found.
	63	This is sometimes useful in locating
	64	disk block numbers by context.
65	.TP
66	.BI \-e " expression"
67	Same as a simple
68	.I expression
69	argument,
70	but useful when the
71	.I expression
72	begins with a \-.
73	.TP
74	.BI \-f " file"
75	The regular expression
76	.RI ( egrep )
77	or string list
78	.RI ( fgrep )
79	is taken from the
80	.I file.
81	.PP
82	In all cases the file name is shown if there is more than one input file.
83	Care should be taken when
84	using the characters
85	$ * [ ^ \| ( ) and \\ in the
86	.I expression
87	as they are
88	also meaningful to the Shell.
89	It is safest to enclose the
90	entire
91	.I expression
92	argument in single quotes \' \'.
93	.PP
94	.I Fgrep
95	searches for lines that contain one of the (newline-separated)
96	.I strings.
97	.PP
98	.I Egrep
99	accepts extended regular expressions.
100	In the following description `character' excludes
101	newline:
102	.IP
103	A \e followed by a single character
104	other than newline
105	matches that character.
106	.IP
107	The character ^ ($) matches the beginning (end) of
108	a line.
109	.IP
110	A
111	.B .
112	matches any character.
113	.IP
114	A single character not otherwise endowed with special
115	meaning matches that character.
116	.IP
117	A string enclosed in brackets [\\|]
118	matches any single character from the string.
119	Ranges of ASCII character codes may be abbreviated
120	as in `a\-z0\-9'.
121	A ]
122	may occur only as the first character of the string.
123	A literal \- must be placed where it can't be
124	mistaken as a range indicator.
125	.IP
126	A regular expression followed by * (+, ?) matches a sequence
127	of 0 or more (1 or more, 0 or 1)
128	matches of the regular expression.
129	.IP
130	Two regular expressions concatenated
131	match a match of the first followed by a match of
132	the second.
133	.IP
134	Two regular expressions separated by \| or newline
135	match either a match for the first or a match for the
136	second.
137	.IP
138	A regular expression enclosed in parentheses
139	matches a match for the regular expression.
140	.LP
141	The order of precedence of operators
142	at the same parenthesis level
143	is [\\|] then
144	*+? then concatenation then \| and newline.
145	.SH "SEE ALSO"
146	ed(1),
147	sed(1),
148	sh(1)
149	.SH DIAGNOSTICS
150	Exit status is 0 if any matches are found,
151	1 if none, 2 for syntax errors or inaccessible files.
152	.SH BUGS
153	Ideally there should be only one
154	.I grep,
155	but we don't know a single algorithm that spans a wide enough
156	range of space-time tradeoffs.
157	.PP
158	Lines
159	are limited to 256 characters;
160	longer lines are truncated.