GREP(1)GREP(1)NAME
grep, egrep, fgrep - search a file for a pattern
SYNOPSIS
grep [ option ] ... expression [ file ] ...
egrep [ option ] ... [ expression ] [ file ] ...
fgrep [ option ] ... [ strings ] [ file ]
DESCRIPTION
Commands of the grep family search the input files (standard input
default) for lines matching a pattern. Normally, each line found is
copied to the standard output. Grep patterns are limited regular
expressions in the style of ed(1); it uses a compact nondeterministic
algorithm. Egrep patterns are full regular expressions; it uses a fast
deterministic algorithm that sometimes needs exponential space. Fgrep
patterns are fixed strings; it is fast and compact. The following
options are recognized.
-v All lines but those matching are printed.
-x (Exact) only lines matched in their entirety are printed (fgrep
only).
-c Only a count of matching lines is printed.
-l The names of files with matching lines are listed (once)
separated by newlines.
-n Each line is preceded by its relative line number in the file.
-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.
-i The case of letters is ignored in making comparisons — that is,
upper and lower case are considered identical. This applies to
grep and fgrep only.
-s Silent mode. Nothing is printed (except error messages). This
is useful for checking the error status.
-w The expression is searched for as a word (as if surrounded by
`\<' and `\>', see ex(1).) (grep only)
-e expression
Same as a simple expression argument, but useful when the
expression begins with a -.
-f file
The regular expression (egrep) or string list (fgrep) is taken
from the file.
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 expression as they are also meaningful to the Shell. It is
safest to enclose the entire expression argument in single quotes ´ ´.
Fgrep searches for lines that contain one of the (newline-separated)
strings.
Egrep accepts extended regular expressions. In the following
description `character' excludes newline:
A \ followed by a single character other than newline matches
that character.
The character ^ matches the beginning of a line.
The character $ matches the end of a line.
A . (period) matches any character.
A single character not otherwise endowed with special meaning
matches that character.
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.
A regular expression followed by an * (asterisk) matches a
sequence of 0 or more matches of the regular expression. A
regular expression followed by a + (plus) matches a sequence of
1 or more matches of the regular expression. A regular
expression followed by a ? (question mark) matches a sequence of
0 or 1 matches of the regular expression.
Two regular expressions concatenated match a match of the first
followed by a match of the second.
Two regular expressions separated by | or newline match either a
match for the first or a match for the second.
A regular expression enclosed in parentheses matches a match for
the regular expression.
The order of precedence of operators at the same parenthesis level is
[] then *+? then concatenation then | and newline.
Ideally there should be only one grep, but we don't know a single
algorithm that spans a wide enough range of space-time tradeoffs.
SEE ALSObm(1), ed(1), sed(1), sh(1)DIAGNOSTICS
Exit status is 0 if any matches are found, 1 if none, 2 for syntax
errors or inaccessible files.
BUGS
Lines are limited to 256 characters; longer lines are truncated.
4th Berkeley Distribution April 29, 1985 GREP(1)