grep - search a file for a pattern grep [ -bchiLlnsv ] [ -e ] pattern | -f patternfile [ file ... ] Grep\^ searches the input files\^ (standard input default) for lines that match the pattern , a regular expression as defined in regexp (6) with the addition of a newline character as an alternative (substitute for | ) with lowest precedence. Normally, each line matching the pattern is `selected', and each selected line is copied to the standard output. The options are

-c Print only a count of matching lines.

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-h Do not print file name tags (headers) with output lines.

-e The following argument is taken as a pattern . This option makes it easy to specify patterns that might confuse argument parsing, such as -n .

-i Ignore alphabetic case distinctions. The implementation folds into lower case all letters in the pattern and input before interpretation. Matched lines are printed in their original form.

-l (ell) Print the names of files with selected lines; don't print the lines.

-L Print the names of files with no selected lines; the converse of -l .

-n Mark each printed line with its line number counted in its file.

-s Produce no output, but return status.

-v Reverse: print lines that do not match the pattern.

-f The pattern argument is the name of a file containing regular expressions one per line.

-b Don't buffer the output: write each output line as soon as it is discovered.

Output lines are tagged by file name when there is more than one input file. (To force this tagging, include /dev/null as a file name argument.)

Care should be taken when using the shell metacharacters $*[^|()=\e and newline in pattern ; it is safest to enclose the entire expression in single quotes \|' \|.\|.\|.\| ' . An expression starting with '*' will treat the rest of the expression as literal characters.

/sys/src/cmd/grep ed (1), awk (1), sed (1), sam (1), regexp (6) Exit status is null if any lines are selected, or non-null when no lines are selected or an error occurs.