The operators in Table A-20 apply when using shopt -s extglob. Matches are case-sensitive, but you may use shopt -s nocasematch (bash 3.1+) to change that. This option affects case and [[ commands.
shopt -s extglob
shopt -s nocasematch
case
Table A-20. extglob extended pattern-matching operators
Grouping
Meaning
@( … )
Only one occurrence
*( … )
Zero or more occurrences
+( … )
One or more occurrences
?( … )
Zero or one occurrences
!( … )
Not these occurrences, but anything else
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