Linux Pocket Guide

Name

egrep [options] pattern [files] — grep

Synopsis

/bin stdin stdout - file -- opt --help --version

The egrep command is just like grep, but uses a different (“extended”) language for regular expressions. It’s the same as grep -E.

Table 1-2. Plain and extended regular expressions for grep

Regular expression	Meaning
.	Any single character.
[…]	Match any single character in this list.
[^…]	Match any single character NOT in this list.
(…)	Grouping.
^	Beginning of a line.
$	End of a line.
\<	Beginning of a word.
\>	End of a word.
[:alnum:]	Any alphanumeric character.
[:alpha:]	Any alphabetic character.
[:cntrl:]	Any control character.
[:digit:]	Any digit.
[:graph:]	Any graphic character.
[:lower:]	Any lowercase letter.
[:print:]	Any printable character.
[:punct:]	Any punctuation mark.
[:space:]	Any whitespace character.
[:upper:]	Any uppercase letter.
[:xdigit:]	Any hexadecimal digit.
*	Zero or more repetitions of a regular expression.
\ c	The character c literally, even if c is a special regular expression character. For example, use \* to match an asterisk or \\ to match a backslash. Alternatively, put the literal character inside square brackets, like [*] or [\].

Table 1-3. Differences: plain and extended regular expressions

Plain	Extended	Meaning
\|	|	Or.
\+	+	One or more repetitions of a regular expression.
\?	?	Zero or one occurrence of a regular expression.
\{ n\}	{ n}	Exactly n repetitions of a regular expression.
\{ n,\}	{ n,}	n or more repetitions of a regular expression.
\{ n, m\}	{ n, m}	Between n and m (inclusive) repetitions of a regular ...