Linux Shell Scripting Cookbook - Third Edition

Other

Here are other characters that fine–tune how a regular expression will be parsed.

()	This treats the terms enclosed as one entity	ma(tri)?x matches max or matrix
|	This specifies alternation-; one of the items on either of side of | should match	Oct (1st | 2nd) matches Oct 1st or Oct 2nd
\	This is the escape character for escaping any of the special characters mentioned previously	a\.b matches a.b, but not ajb; it ignores the special meaning of . because of \

For more details on the regular expression components available, you can refer to http://www.linuxforu.com/2011/04/sed-explained-part-1/.