NAME

grep − search a file for a pattern

SYNOPSIS

­grep [ ­option ...  ] ­pattern [ ­file ...  ]

DESCRIPTION

­Grep searches the input ­files (standard input default) for lines (with newlines excluded) that match the pattern, a regular expression as defined in regexp(6). 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. 

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

­-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. 

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 ­$∗[^|()=\ and newline in pattern; it is safest to enclose the entire expression in single quotes ’...’. 

SOURCE

­/sys/src/cmd/grep.c

SEE ALSO

ed(1), awk(1), sed(1), sam(1), regexp(6)

DIAGNOSTICS

Exit status is null if any lines are selected, or non-null when no lines are selected or an error occurs. 

Plan 9  —  April 04, 1995