1GREP(1) General Commands Manual GREP(1)
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6 grep, egrep, fgrep - search a file for a pattern
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9 grep [ option ] ... expression [ file ] ...
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11 egrep [ option ] ... [ expression ] [ file ] ...
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13 fgrep [ option ] ... [ strings ] [ file ]
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16 Commands of the grep family search the input files (standard input
17 default) for lines matching a pattern. Normally, each line found is
18 copied to the standard output. Grep patterns are limited regular
19 expressions in the style of ex(1); it uses a compact nondeterministic
20 algorithm. Egrep patterns are full regular expressions; it uses a fast
21 deterministic algorithm that sometimes needs exponential space. Fgrep
22 patterns are fixed strings; it is fast and compact. The following
23 options are recognized.
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25 -v All lines but those matching are printed.
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27 -x (Exact) only lines matched in their entirety are printed (fgrep
28 only).
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30 -c Only a count of matching lines is printed.
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32 -l The names of files with matching lines are listed (once) sepa‐
33 rated by newlines.
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35 -n Each line is preceded by its relative line number in the file.
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37 -b Each line is preceded by the block number on which it was found.
38 This is sometimes useful in locating disk block numbers by con‐
39 text.
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41 -i The case of letters is ignored in making comparisons — that is,
42 upper and lower case are considered identical. This applies to
43 grep and fgrep only.
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45 -s Silent mode. Nothing is printed (except error messages). This
46 is useful for checking the error status.
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48 -w The expression is searched for as a word (as if surrounded by
49 `\<' and `\>', see ex(1).) (grep only)
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51 -e expression
52 Same as a simple expression argument, but useful when the
53 expression begins with a -.
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55 -f file
56 The regular expression (egrep) or string list (fgrep) is taken
57 from the file.
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59 In all cases the file name is shown if there is more than one input
60 file. Care should be taken when using the characters $ * [ ^ | ( ) and
61 \ in the expression as they are also meaningful to the Shell. It is
62 safest to enclose the entire expression argument in single quotes ´ ´.
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64 Fgrep searches for lines that contain one of the (newline-separated)
65 strings.
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67 Egrep accepts extended regular expressions. In the following descrip‐
68 tion `character' excludes newline:
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70 A \ followed by a single character other than newline matches
71 that character.
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73 The character ^ matches the beginning of a line.
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75 The character $ matches the end of a line.
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77 A . (period) matches any character.
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79 A single character not otherwise endowed with special meaning
80 matches that character.
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82 A string enclosed in brackets [] matches any single character
83 from the string. Ranges of ASCII character codes may be abbre‐
84 viated as in `a-z0-9'. A ] may occur only as the first charac‐
85 ter of the string. A literal - must be placed where it can't be
86 mistaken as a range indicator.
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88 A regular expression followed by an * (asterisk) matches a
89 sequence of 0 or more matches of the regular expression. A reg‐
90 ular expression followed by a + (plus) matches a sequence of 1
91 or more matches of the regular expression. A regular expression
92 followed by a ? (question mark) matches a sequence of 0 or 1
93 matches of the regular expression.
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95 Two regular expressions concatenated match a match of the first
96 followed by a match of the second.
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98 Two regular expressions separated by | or newline match either a
99 match for the first or a match for the second.
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101 A regular expression enclosed in parentheses matches a match for
102 the regular expression.
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104 The order of precedence of operators at the same parenthesis level is
105 [] then *+? then concatenation then | and newline.
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107 Ideally there should be only one grep, but we don't know a single algo‐
108 rithm that spans a wide enough range of space-time tradeoffs.
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111 ex(1), sed(1), sh(1)
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114 Exit status is 0 if any matches are found, 1 if none, 2 for syntax
115 errors or inaccessible files.
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118 Lines are limited to 256 characters; longer lines are truncated.
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1224th Berkeley Distribution April 29, 1985 GREP(1)