NAME

grep − search a file for a pattern

SYNOPSIS

grep [options] limited regular expression [file ...]

DESCRIPTION

grep searches files for a pattern and prints all lines that contain that pattern.  grep uses limited regular expressions (expressions that have string values that use a subset of the possible alphanumeric and special characters) like those used with ed (1) to match the patterns.  It uses a compact non-deterministic algorithm. 

Be careful using the characters $, ∗, [, ^, │, (, ), and \ in the limited regular expression because they are also meaningful to the shell.  It is safest to enclose the entire limited regular expression in single quotes ′...′. 

If no files are specified, grep assumes standard input.  Normally, each line found is copied to standard output.  The file name is printed before each line found if there is more than one input file. 

Command line options are:

−b Precede each line by the block number on which it was found.  This can be useful in locating block numbers by context (first block is 0). 

−c Print only a count of the lines that contain the pattern. 

−i Ignore upper/lower case distinction during comparisons. 

−l Print the names of files with matching lines once, separated by new-lines.  Does not repeat the names of files when the pattern is found more than once. 

−n Precede each line by its line number in the file (first line is 1). 

−s Suppress error messages about nonexistent or unreadable files

−v Print all lines except those that contain the pattern. 

SEE ALSO

ed(1), egrep(1), fgrep(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 (even if matches were found). 

BUGS

Lines are limited to BUFSIZ characters; longer lines are truncated.  BUFSIZ is defined in /usr/include/stdio.h. 
If there is a line with embedded nulls, grep will only match up to the first null; if it matches, it will print the entire line. 

September 02, 1992