POSTIN
/bin/sh
perl -pi -e 's/\A-\s+GL:/ GL:/' /etc/X11/app-defaults/XScreenSaver
POSTUN
/bin/sh
perl -ni -e '/\A\s*GL:/ and print "- $_" or print "$_"' /etc/X11/app-defaults/XScreenSaver
/bin/sh
perl -pi -e 's/\A-\s+GL:/ GL:/' /etc/X11/app-defaults/XScreenSaver
/bin/sh
perl -ni -e '/\A\s*GL:/ and print "- $_" or print "$_"' /etc/X11/app-defaults/XScreenSaver