Learning_the_bash_Shell_Third_Edition 7/n(chapter 4, page[117|99])

Extended Pattern Matching

Operator	Meaning
*(patternlist)	Matches zero or more occurrences of the given patterns.
+(patternlist)	Matches one or more occurrences of the given patterns.
?(patternlist)	Matches zero or one occurrences of the given patterns.
@(patternlist)	Matches exactly one of the given patterns.
!(patternlist)	Matches anything except one of the given patterns.

 

Some examples of these include:

• *(alice|hatter|hare) would match zero or more occurrences of alice, hatter, and hare. So it would match the null string, alice, alicehatter, etc.

• +(alice|hatter|hare) would do the same except not match the null string.

• ?(alice|hatter|hare) would only match the null string, alice, hatter, or hare.

• @(alice|hatter|hare) would only match alice, hatter, or hare.

• !(alice|hatter|hare) matches everything except alice, hatter, and hare.

The values provided can contain shell wildcards too. So, for example, +([0-9]) matches a number of one or more digits. The patterns can also be nested, so you could remove all files except those beginning with vt followed by a number by doing rm !(vt+([0-9])).