package/mender/S42mender: fix check-pkg and shellcheck warnings

Copy the basic syntax of package/polkit/S50polkit and change the following:

  - Add DAEMON, DAEMON_PATH, PIDFILE and DAEMON_ARGS variables.
  - Fix shellcheck warning SC2166 on line 16.
  - Fix shellcheck warning SC2181 on lines 29 and 34 by assigning the return
    code from the start-stop-daemon binary to a variable, and then check the
    value of the variable.

Signed-off-by: Adam Duskett <aduskett@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/mender/S42mender

@@ -2,6 +2,10 @@
 #
 # Starts mender service.
 #
+DAEMON="mender"
+DAEMON_PATH="/usr/bin/mender"
+PIDFILE="/var/run/${DAEMON}.pid"
+DAEMON_ARGS="-daemon"
 
 start() {
 	# If /var/lib/mender is a symlink to /var/run/mender, and
@@ -9,8 +13,7 @@ start() {
 	#     create the directory pointed to by the symlink.
 	#   - the filesystem is RW (i.e. we can rm the symlink),
 	#     replace the symlink with an actual directory
-	if [ -L /var/lib/mender \
-	     -a "$(readlink /var/lib/mender)" = "/var/run/mender" ]
+	if [ -L /var/lib/mender ] && [ "$(readlink /var/lib/mender)" = "/var/run/mender" ]
 	then
 		if rm -f /var/lib/mender >/dev/null 2>&1; then
 			mkdir -p /var/lib/mender
@@ -23,15 +26,16 @@ start() {
 
 	printf "Starting mender service: "
 	umask 077
-
-	start-stop-daemon -S -q -b -m -p /var/run/mender.pid \
-		--exec /usr/bin/mender -- daemon
-	[ $? = 0 ] && echo "OK" || echo "FAIL"
+	start-stop-daemon -bmSqp "$PIDFILE" -x ${DAEMON_PATH} -- ${DAEMON_ARGS}
+	status=$?
+	[ "${status}" = 0 ] && echo "OK" || echo "FAIL"
 }
+
 stop() {
 	printf "Stopping mender service: "
-	start-stop-daemon -K -q -p /var/run/mender.pid
-	[ $? = 0 ] && echo "OK" || echo "FAIL"
+	start-stop-daemon -Kqp "$PIDFILE"
+	status=$?
+	[ "${status}" = 0 ] && echo "OK" || echo "FAIL"
 }
 restart() {
 	stop
@@ -49,7 +53,7 @@ case "$1" in
 		restart
 		;;
 	*)
-		echo "Usage: $0 {start|stop|restart}"
+		echo "Usage: $0 {start|stop|reload|restart}"
 		exit 1
 esac