$ ack  -A0 "[^-]\btext" NUL foobar.pl
ack: NUL: No such file or directory
foobar.pl
153:   $left_frame->Label(text => "Perl Chat Client v$VERSION")
172:   $right_frame->Label(text => 'Buddies')
200:      print CONF "# You may edit this file with a text editor or\n";
852:        # $request is the text of the request
853:        # put text of reply into $outbuffer{$client}
1221:      print CONF "# You may edit this file with a text editor or\n";