Unify shell script style

bin/screenshot.sh

@@ -1,5 +1,5 @@
 #!/bin/sh
-# env
+# screenshot
 # Written in 2019 by Lucas
 # CC0 1.0 Universal/Public domain - No rights reserved
 #
@@ -10,7 +10,8 @@
 # Dedication along with this software. If not, see
 # <http://creativecommons.org/publicdomain/zero/1.0/>.
 
-usage() {
+usage()
+{
 	cat - <<. >&2
 Usage:
 	${0##*/}
@@ -21,30 +22,25 @@ Usage:
 	exit 1
 }
 
-save_screenshot() {
+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)	if [ "$1" != "-window" ]; then
-		printf "%s: Unknown option \"%s\".\n" \
-		    "${0##*/}" "$1" >&2
-		exit 1
-	fi
+1)	[ "$1" = "-window" ] || err "Unknown option \"$1\"."
 	xwd -silent | save_screenshot
 	;;
-2)	if [ "$1" != "-id" ] && [ "$1" != "-name" ]; then
-		printf "%s: Unknown option \"%s\".\n" \
-		    "${0##*/}" "$1" >&2
-		exit 1
-	fi
-	if [ -z "$2" ]; then
-		printf "%s: %s expects a non-empty parameter.\n" \
-		    "${0##*/}" "$1" >&2
-		exit 1
-	fi
+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