bash中 @(a|b)是什么意思？

netcafe

看到在bash_completion中：
if [[ ${COMP_WORDS} == @(install|remove|autoremove|purge|source|build-dep) ]];
请教这句中的 @(install|remove|autoremove|purge|source|build-dep) 作何解释？

blackold

pattern match

greendays

bash里面有这个脚本吗？  能贴出来看看不？

hotsnow

Pattern Matching

       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 back‐
       slash 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.  When the 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 subdirectories.  If followed by a /, two adjacent *s will match only directories and subdirecto‐
              ries.
       ?      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 sorts between those two  charac‐
              ters, 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.  The sorting order of characters in range expressions is determined by the current locale and the value of the LC_COLLATE shell  variable,  if
              set.  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.

              Within [ and ], character classes can be specified using the syntax [:class:], 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.  The word character class matches letters, digits, and the character _.

              Within  [  and  ], an equivalence class can be specified using the syntax [=c=], which matches all characters with the same collation weight (as defined by the current
              locale) as the character c.

              Within [ and ], the syntax [.symbol.] matches the collating symbol symbol.

       If the extglob shell option is enabled using the shopt 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 sub-patterns:

              ?(pattern-list)
                     Matches zero or one occurrence of the given patterns
              *(pattern-list)
                     Matches zero or more occurrences of the given patterns
              +(pattern-list)
                     Matches one or more occurrences of the given patterns
              @(pattern-list)
                     Matches one of the given patterns
              !(pattern-list)
                     Matches anything except one of the given patterns