在我的 中/var/log/syslog，我看到（过滤掉不相关的部分）：
Dec 30 15:00:10 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 15:13:11 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 15:26:11 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 15:39:12 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 15:52:13 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 16:05:13 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 16:18:14 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 16:25:41 myhost systemd[1]: Started CUPS Scheduler.
Dec 30 16:31:15 myhost systemd[1]: Started CUPS Scheduler.
也就是说，每隔几分钟，systemd 就会启动 CUPS 调度程序。我没有看到任何有关失败的消息，但是：
# service cups status
● cups.service - CUPS Scheduler
Loaded: loaded (/lib/systemd/system/cups.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Fri 2016-12-30 18:55:53 CET; 2min 43s ago
Docs: man:cupsd(8)
Process: 30684 ExecStart=/usr/sbin/cupsd -l (code=exited, status=0/SUCCESS)
Main PID: 30684 (code=exited, status=0/SUCCESS)
现在，/var/log/cups/error_log是空的，并/var/log/cups/access_log显示：
localhost - - [30/Dec/2016:15:27:21 +0100] "POST / HTTP/1.1" 200 186 Renew-Subscription successful-ok
localhost - - [30/Dec/2016:16:25:41 +0100] "POST / HTTP/1.1" 200 186 Renew-Subscription successful-ok
localhost - - [30/Dec/2016:17:24:01 +0100] "POST / HTTP/1.1" 200 186 Renew-Subscription successful-ok
localhost - - [30/Dec/2016:18:22:21 +0100] "POST / HTTP/1.1" 200 186 Renew-Subscription successful-ok
这很可能对应于重新启动。我实际上没有将打印机或扫描仪连接到这台机器。
为什么会发生这种情况？