env/bin/screenshot.sh

#!/bin/sh
# screenshot
# Written in 2019-2020 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
}

case $# in
0)	set -- -root
	;;
1)	[ "$1" = "-window" ] || err "unknown option $1"
	set --
	;;
2)	[ "$1" = "-id" ] || [ "$1" = "-name" ] || err "unknown option $1"
	[ -n "$2" ] || err "$1 expects a non-empty parameter"
	;;
*)	usage
	;;
esac

: ${SCREENSHOTS:=~/media/ss}
xwd -silent "$@" | xwdtopnm |
    pnmtopng >"$SCREENSHOTS/$(date +%Y%m%d-%H%M%S).png"