env/bin/screenshot.sh

#!/bin/sh
# screenshot
# Written in 2019 by Lucas
# CC0 1.0 Universal/Public domain - No rights reserved
#
# To the extent possible under law, the author(s) have dedicated all
# copyright and related and neighboring rights to this software to the
# public domain worldwide. This software is distributed without any
# warranty. You should have received a copy of the CC0 Public Domain
# Dedication along with this software. If not, see
# <http://creativecommons.org/publicdomain/zero/1.0/>.

usage()
{
	cat - <<. >&2
Usage:
	${0##*/}
	${0##*/} -id id
	${0##*/} -name name
	${0##*/} -window
.
	exit 1
}

err()
{
	printf "%s: %s\n" "${0##*/}" "$*" >&2
	exit 1
}

save_screenshot()
{
	xwdtopnm | pnmtopng >~/media/ss/"$(date +%Y%m%d-%H%M%S)".png
}

case $# in
0)	xwd -silent -root | save_screenshot
	;;
1)	[ "$1" = "-window" ] || err "Unknown option \"$1\"."
	xwd -silent | save_screenshot
	;;
2)	[ "$1" = "-id" ] || [ "$1" = "-name" ] || err "Unknown option \"$1\"."
	[ -n "$2" ] || err "$1 expects a non-empty parameter."
	xwd -silent "$1" "$2" | save_screenshot
	;;
*)	usage
	;;
esac