Linux in a Nutshell, 6th Edition

Search Patterns

The characters in the following table have special meaning only in search patterns.

Character	Pattern
.	Match any single character except newline. Can match newline in gawk.
*	Match any number (or none) of the single character that immediately precedes it. The preceding character can also be a regular expression. For example, since . (dot) means any character, .* means “match any number of any character.”
^	Match the following regular expression at the beginning of the line or string.
$	Match the preceding regular expression at the end of the line or string.
[ ]	Match any one of the enclosed characters. A hyphen (-) indicates a range of consecutive characters. A circumflex (^) as the first character in the brackets reverses the sense: it matches any one character not in the list. A hyphen or close bracket (]) as the first character is treated as a member of the list. All other metacharacters are treated as members of the list (i.e., literally).
{n,m}	Match a range of occurrences of the single character that immediately precedes it. The preceding character can also be a regular expression. {n} matches exactly n occurrences, {n,} matches at least n occurrences, and {n,m} matches any number of occurrences between n and m. n and m must be between 0 and 255, inclusive. (The GNU programs on Linux allow a range of 0 to 32767.)
\{n,m\}	Just like {n,m}, earlier, but with backslashes in front of the braces.
\	Turn off the special meaning of the following character.
\( \)	Save the subpattern enclosed ...