For example: declare -A foo foo['ab]']=bar
will work perfectly fine, but: declare -A foo foo=( ['ab]']=bar ) will end with following error: -bash: [ab]]=bar: bad array subscript Same with double quotes, or backslash quoting. It's still possible to quote that right bracket with backslash inside single quotes, but while it will do the assignment without errors, the key will be different. There's no mention in documentation about () specific constraints, so it looks like a small bug. Tested with: BASH_VERSINFO=([0]="4" [1]="2" [2]="10" [3]="2" [4]="release" [5]="i686-pc-linux-gnu") BASH_VERSION='4.2.10(2)-release' p.s. keep me in CC, as I'm not subscribed
