The apostrophes ensure the entire expression is evaluated by grep instead of by the user's shell. The caret ' ^ ' matches the null string at the beginning of a line, and the ' ' escapes the ' . ', which would otherwise match any character. Linux grep command usage with examples. The grep command which stands for "global regular expression print," processes text line by line and prints any lines which match a specified pattern. The grep command is used to search text or searches the given file for lines containing a match to the given strings or words. GREP(1) GREP(1) NAME grep, egrep, fgrep - print lines matching a pattern SYNOPSIS grep Grep understands two different versions of regular expres- sion syntax: ``basic'' and ``extended.'' In GNU grep Grep command in Unix/Linux is the short form of 'global search for the regular expression'. The grep command is a filter that is used to search for lines matching a specified pattern and print the matching lines to standard output. How to grep a tab on Linux? tagged Bash, Command, Command line, Howto, Linux, Programming, Tutorial. The grep command is used to find patterns in files. This tutorial shows how it can be useful for developers to find their way into a new codebase. I am going to share with you how to use grep command in Linux with examples. I let you check the sort command manual for the exact meaning of GNU grep - GNU Grep: Print lines matching a pattern Free Software Foundation last updated December 29, 2018. This manual (grep) is available in the following formats: HTML (192K bytes) - entirely on one web page. HTML - with one web page per node. HTML compressed (40K gzipped characters) - entirely on one web page. This section of the Linux tutorial teaches the basics of regular expressions and grep on the Linux command line. Examples, tips and practice activities. grep. Search file(s) for specific text. Related linux commands: egrep - Search file(s) for lines that match an extended expression