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 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).
|
| {n,m} |
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.
|
| \{n,m\} | Just like
{n,m},
above, but with backslashes in front of the braces.
|
| \ | Turn off the special meaning of the character that follows. |
| \( \) |
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.
|
| \n | 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 one or more instances of preceding regular expression. |
| ? | 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.
|
