detect systemctl in install release script

release/install-release.sh

@@ -59,12 +59,15 @@ if [ ! -f "/etc/v2ray/config.json" ]; then
   echo "UUID:${UUID}"
 fi
 
-if [ -d "/lib/systemd/system" ]; then
+SYSTEMCTL_CMD=$(command -v systemctl)
+SERVICE_CMD=$(command -v service)
+
+if [ -n "${SYSTEMCTL_CMD}" ]; then
   if [ ! -f "/lib/systemd/system/v2ray.service" ]; then
     cp "/tmp/v2ray/v2ray-${VER}-linux-${VDIS}/systemd/v2ray.service" "/lib/systemd/system/"
     systemctl enable v2ray
   fi
-elif [ -d "/etc/init.d" ]; then # Configure SysV if necessary.
+elif [ -n "${SERVICE_CMD}" ]; then # Configure SysV if necessary.
   if [ ! -f "/etc/init.d/v2ray" ]; then
     cp "/tmp/v2ray/v2ray-${VER}-linux-${VDIS}/systemv/v2ray" "/etc/init.d/v2ray"
     chmod +x "/etc/init.d/v2ray"