使用systemctl获取systemd进程的正常运行时间或停机时间？

Question

就像使用

systemctl is-active <servicename>

给出的是，如果服务处于活动状态或失败，那么是否可以使用 systemctl 来获取 systemd 服务的正常运行时间或停机时间？

time systemctl status kdm|cat
* kdm.service - LSB: X display manager for KDE
   Loaded: loaded (/etc/init.d/kdm; generated; vendor preset: enabled)
   Active: active (exited) since Wed 2017-06-21 12:03:26 CEST; 1h 42min ago
     Docs: man:systemd-sysv-generator(8)
    Tasks: 0 (limit: 4915)
   CGroup: /system.slice/kdm.service

是否可以使用systemctl获取1h 42min

Answer 1

使用带选项 -P 和 -o 的 GNU grep

systemctl status kdm | grep -Po ".*; \K(.*)(?= ago)"

Answer 2

使用systemctl的属性WatchdogTimestamp

 blr8-100-208-Vin:~ # systemctl show novell-nss --property WatchdogTimestamp
 WatchdogTimestamp=Tue 2020-11-24 17:30:20 IST

Answer 3

获取 systemd 单元上次进入“活动”阶段的时间戳：

systemctl show --property=ActiveEnterTimestamp kdm