Match any single character except newline. Can match newline in awk.

Match any number (or none) of the single character that immediately precedes it. The preceding character can also be a regular expression; e.g., 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).

Match a range of occurrences of the single character that immediately precedes it. The preceding character can also be a metacharacter. {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.

Just like {n,m}, above, but with backslashes in front of the braces.

Save the pattern enclosed between \( and \) into a special holding space. Up to nine patterns can be saved on a single line. The text matched by the subpatterns can be “replayed” in substitutions by the escape sequences \1 to \9.

Replay the nth subpattern enclosed in \( and \) into the pattern at this point. n is a number from 1 to 9, with 1 starting on the left. See the following Examples.

Match characters at beginning (\<) or end (\>) of a word.

Match zero or one instances of preceding regular expression.

Match the regular expression specified before or after.

Apply a match to the enclosed group of regular expressions.

Alphanumeric characters

Alphabetic characters

Space or tab

Control characters

Decimal digits

Nonspace characters

Lowercase characters

Printable characters

Whitespace characters

Uppercase characters

Hexadecimal digits

Turn off the special meaning of the character that follows.

Restore the text matched by the nth pattern previously saved by \( and \). n is a number from 1 to 9, with 1 starting on the left.

Reuse the text matched by the search pattern as part of the replacement pattern.

Reuse the previous replacement pattern in the current replacement pattern. Must be the only character in the replacement pattern. (ex and vi)

Reuse the previous replacement pattern in the current replacement pattern. Must be the only character in the replacement pattern. (ed)

Convert first character of replacement pattern to uppercase.

Convert entire replacement pattern to uppercase.

Convert first character of replacement pattern to lowercase.

Convert entire replacement pattern to lowercase.

Turn off previous \u, \U, \l, and \L.