我尝试安装 squid，但尝试重新启动 squid 时出现以下错误
无法重新启动 squid.service：任何 .service 文件均未提供名称 org.freedesktop.PolicyKit1，请参阅系统日志和“systemctl status squid.service”了解详情。
当我运行systemctl status squid.service
结果是
● squid.service - LSB: Squid HTTP Proxy version 3.x
Loaded: loaded (/etc/init.d/squid; generated; vendor preset: enabled)
Active: active (running) since Fri 2017-12-01 22:40:20 GMT; 48min ago
Docs: man:systemd-sysv-generator(8)
Main PID: 2090 (squid)
CGroup: /system.slice/squid.service
├─2088 /usr/sbin/squid -YC -f /etc/squid/squid.conf
├─2090 (squid-1) -YC -f /etc/squid/squid.conf
├─2091 (logfile-daemon) /var/log/squid/access.log
└─2092 (pinger)
Dec 01 22:40:18 myserver systemd[1]: Starting LSB: Squid HTTP Proxy version 3.x...
Dec 01 22:40:19 myserver squid[2088]: Squid Parent: will start 1 kids
Dec 01 22:40:19 myserver squid[2088]: Squid Parent: (squid-1) process 2090 started
Dec 01 22:40:19 myserver squid[2049]: Starting Squid HTTP Proxy: squid.
Dec 01 22:40:19 myserver systemd[1]: squid.service: PID file /var/run/squid.pid not readable (yet?)
Dec 01 22:40:19 myserver systemd[1]: squid.service: Supervising process 2090 which is not our child
Dec 01 22:40:20 myserver systemd[1]: Started LSB: Squid HTTP Proxy version 3.x.
Dec 01 22:40:20 myserver systemd[1]: squid.service: Supervising process 2090 which is not our child
我应该做什么？只是尝试设置缓存代理，但知识有限……
Dec 01 22:40:19 myserver squid[2088]: Squid Parent: (squid-1) process 2090 started
Dec 01 22:40:19 myserver squid[2049]: Starting Squid HTTP Proxy: squid.
Dec 01 22:40:19 myserver systemd[1]: squid.service: PID file /var/run/squid.pid not readable (yet?) after start: No such file or directory
Dec 01 22:40:19 myserver systemd[1]: squid.service: Supervising process 2090 which is not our child. We'll most likely not notice when it exits.
Dec 01 22:40:20 myserver systemd[1]: Started LSB: Squid HTTP Proxy version 3.x.
Dec 01 22:40:20 myserver systemd[1]: squid.service: Supervising process 2090 which is not our child. We'll most likely not notice when it exits.
Dec 01 23:39:05 myserver systemd[1]: squid.service: Main process exited, code=killed, status=9/KILL
Dec 01 23:39:07 myserver squid[2796]: Stopping Squid HTTP Proxy: squid.
Dec 01 23:39:07 myserver systemd[1]: squid.service: Unit entered failed state.
Dec 01 23:39:07 myserver systemd[1]: squid.service: Failed with result 'signal'.