Any character that appears in a pattern, other than the special pattern characters described below, matches itself. The NUL character may not occur in a pattern. A backslash escapes the following character; the escaping backslash is discarded when matching. The special pattern characters must be quoted if they are to be matched literally.
The special pattern characters have the following meanings:
Matches any string, including the null string.
globstar shell option is enabled, and ‘*’ is used in
a filename expansion context, two adjacent ‘*’s used as a single
pattern will match all files and zero or more directories and
If followed by a ‘/’, two adjacent ‘*’s will match only
directories and subdirectories.
Matches any single character.
Matches any one of the enclosed characters. A pair of characters
separated by a hyphen denotes a range expression;
any character that falls between those two characters, inclusive,
using the current locale’s collating sequence and character set,
is matched. If the first character following the
‘[’ is a ‘!’ or a ‘^’
then any character not enclosed is matched. A ‘-’
may be matched by including it as the first or last character
in the set. A ‘]’ may be matched by including it as the first
character in the set.
The sorting order of characters in range expressions is determined by
the current locale and the values of the
LC_ALL shell variables, if set.
For example, in the default C locale, ‘[a-dx-z]’ is equivalent to
‘[abcdxyz]’. Many locales sort characters in dictionary order, and in
these locales ‘[a-dx-z]’ is typically not equivalent to ‘[abcdxyz]’;
it might be equivalent to ‘[aBbCcDdxXyYz]’, for example. To obtain
the traditional interpretation of ranges in bracket expressions, you can
force the use of the C locale by setting the
LC_ALL environment variable to the value ‘C’, or enable the
globasciiranges shell option.
Within ‘[’ and ‘]’, character classes can be specified
using the syntax
:], where class is one of the
following classes defined in the POSIX standard:
alnum alpha ascii blank cntrl digit graph lower print punct space upper word xdigit
A character class matches any character belonging to that class.
word character class matches letters, digits, and the character
Within ‘[’ and ‘]’, an equivalence class can be
specified using the syntax
matches all characters with the same collation weight (as defined
by the current locale) as the character c.
Within ‘[’ and ‘]’, the syntax
matches the collating symbol symbol.
extglob shell option is enabled using the
builtin, several extended pattern matching operators are recognized.
In the following description, a pattern-list is a list of one
or more patterns separated by a ‘|’.
Composite patterns may be formed using one or more of the following
Matches zero or one occurrence of the given patterns.
Matches zero or more occurrences of the given patterns.
Matches one or more occurrences of the given patterns.
Matches one of the given patterns.
Matches anything except one of the given patterns.
Complicated extended pattern matching against long strings is slow, especially when the patterns contain alternations and the strings contain multiple matches. Using separate matches against shorter strings, or using arrays of strings instead of a single long string, may be faster.