>perl -wMstrict -le
"my $s = 'foo [bar baz] quux [%^&*] boff [] biff';
 my @bracketed = $s =~ m{ \[ ([^]]*) \] }xmsg;
 print qq{'$_'} for @bracketed;
 @bracketed = $s =~ m{ \[ [^]]* \] }xmsg;
 print qq{'$_'} for @bracketed;
"
'bar baz'
'%^&*'
''
'[bar baz]'
'[%^&*]'
'[]'