Linux Shells by Example

3.2. Extended grep (grep -E or egrep)

The main advantage of using extended grep is that additional regular expression metacharacters (see Table 3.4) have been added to the basic set. With the -E extension, Gnu grep allows the use of these new metacharacters.

Table 3.5. egrep's Regular Expression Metacharacters

Metacharacter	Function	Example	What It Matches
^	Beginning of line anchor	^love	Matches all lines beginning with love.
$	End of line anchor	love$	Matches all lines ending with love.
.	Matches one character	l..e	Matches lines containing an l, followed by two characters, followed by an e.
*	Matches zero or more characters	*love	Matches lines with zero or more spaces, of the preceding characters followed by the pattern love.
[ ]	Matches one ...