grep(1) [v7 man page]
GREP(1) General Commands Manual 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; unless the -h flag is used, the file name is shown if there is more than one input file. 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. -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 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 con- text. -s No output is produced, only status. -h Do not print filename headers with output lines. -y Lower case letters in the pattern will also match upper case letters in the input (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. -x (Exact) only lines matched in their entirety are printed (fgrep only). 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 matches that character. The character ^ ($) matches the beginning (end) of a line. A . 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 * (+, ?) matches a sequence of 0 or more (1 or more, 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. SEE ALSO
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
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. Lines are limited to 256 characters; longer lines are truncated. GREP(1)
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grep(1) General Commands Manual grep(1) Name grep, egrep, fgrep - search file for regular expression Syntax grep [option...] expression [file...] egrep [option...] [expression] [file...] fgrep [option...] [strings] [file] Description Commands of the family search the input files (standard input default) for lines matching a pattern. Normally, each line found is copied to the standard output. The command patterns are limited regular expressions in the style of which uses a compact nondeterministic algorithm. The command patterns are full regular expressions. The command uses a fast deterministic algorithm that sometimes needs exponential space. The command pat- terns are fixed strings. The command is fast and compact. In all cases the file name is shown if there is more than one input file. Take care when using the characters $ * [ ^ | ( ) and in the expression because they are also meaningful to the Shell. It is safest to enclose the entire expression argument in single quotes ' '. The command searches for lines that contain one of the (new line-separated) strings. The command accepts extended regular expressions. In the following description `character' excludes new line: A followed by a single character other than new line matches that character. The character ^ matches the beginning of a line. The character $ matches the end of a line. A . (dot) 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 new line 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 the following: [], then *+?, then concatenation, then | and new line. Options -b Precedes each output line with its block number. This is sometimes useful in locating disk block numbers by context. -c Produces count of matching lines only. -e expression Uses next argument as expression that begins with a minus (-). -f file Takes regular expression (egrep) or string list (fgrep) from file. -i Considers upper and lowercase letter identical in making comparisons and only). -l Lists files with matching lines only once, separated by a new line. -n Precedes each matching line with its line number. -s Silent mode and nothing is printed (except error messages). This is useful for checking the error status (see DIAGNOSTICS). -v Displays all lines that do not match specified expression. -w Searches for an expression as for a word (as if surrounded by `<' and `>'). For further information, see only. -x Prints exact lines matched in their entirety only). Restrictions Lines are limited to 256 characters; longer lines are truncated. Diagnostics Exit status is 0 if any matches are found, 1 if none, 2 for syntax errors or inaccessible files. See Also ex(1), sed(1), sh(1) grep(1)