https://linux.cn/article-5926-1.html
列出所有服务（包括启用的和禁用的）
systemctl list-unit-files –type=service
systemctl start httpd.service
systemctl restart httpd.service
systemctl stop httpd.service
systemctl reload httpd.service
systemctl status httpd.service
系统启动时自动启动服务
systemctl enable httpd.service
systemctl disable httpd.service
使用systemctl命令杀死服务
systemctl kill httpd
systemctl status httpd
按CPU、内存、输入和输出列出控制组