Check service status with systemctl.
USAGE: ./check_systemctl -s <service_name> [OPTIONS]
OPTIONS:
-e | --expected-status
The expected service status: active | inactive.
Defaults: active
-h | --help
Display this help.
-s | --service
The name of the service to check, e.g. nginx or nginx.service.
-v | --version
Display script version.