systemctl is-enabled *.service #Query whether the service is started at boot
systemctl enable *.service #Start running the service
systemctl disable *.service #Cancel startup operation
systemctl start *.service #Start service
systemctl stop *.service #Stop the service
systemctl restart *.service #Restart the service
systemctl reload *.service #Reload the service configuration file
systemctl status *.service #Query service running status
systemctl --failed #Display services that failed to start
Note: * represents the name of a service, for example, the service name of http is httpd
Docker centos7.x runs the systemctl command abnormally
$ systemctl status firewalld.service
Failed to get D-Bus connection: Operation not permitted
Solution:
docker run -itd --privileged --name docker-centos centos:latest /usr/sbin/init
$ systemctl start firewalld.service
Failed to start firewalld.service: Unit not found
Solution:
$ yum install firewalld