grep

The acronym grep is a standard UNIX search command that stands for "general regular expression parser." It allows users to search files for particular patterns, including so-called regular expressions which can utilize various substitutions and wildcards to provide powerful search-and-replace operations within files.

Grep is also a UNIX command that stands for "get regular expression print." Grep searches for a particular string and prints the lines containing those characters to the screen. A somewhat similar command, more, prints a complete file a screen at a time.

URLs:

Quick Guide to UNIX commands #2

Detail:

The normal format for grep is:

grep (options) expression filename (filename2 filename3 ....)

Some of these options are:

• -v All lines but those matching are printed.
• -x (Exact) only lines matched in their entirety are printed (fgrep only).
• -c Only a count of matching lines is printed.
• -n Each line is preceded by its relative line number in the file.
• -i The case of letters is ignored in making comparisons - that is, upper and lower case are considered identical.

Like all UNIX commands, it is case sensitive.

Type "man grep" at a UNIX prompt to obtain the reference manual entry on the grep command with a complete list of command options.