在安装了 Ubuntu 20.04 LTS 的笔记本电脑上，当无人看管数十分钟/小时时，有时我会发现它已注销。在网上搜索后，我发现可以在 中找到这些行为的痕迹/var/log/auth.log。这是我认为发生注销的时间片段：
... more of the same ...
Aug 17 13:35:01 <_my_user_> CRON[3157490]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 13:35:01 <_my_user_> CRON[3157490]: pam_unix(cron:session): session closed for user root
Aug 17 13:45:01 <_my_user_> CRON[3158676]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 13:45:01 <_my_user_> CRON[3158676]: pam_unix(cron:session): session closed for user root
Aug 17 13:55:01 <_my_user_> CRON[3159724]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 13:55:01 <_my_user_> CRON[3159724]: pam_unix(cron:session): session closed for user root
Aug 17 14:03:49 <_my_user_> dbus-daemon[945]: [system] Rejected send message, 0 matched rules; type="method_return", sender=":1.83" (uid=1000 pid=2383 comm="/usr/bin/pulseaudio --daemonize=no --log-target=jo" label="unconfined") interface="(unset)" member="(unset)" error name="(unset)" requested_reply="0" destination=":1.2" (uid=0 pid=940 comm="/usr/lib/bluetooth/bluetoothd " label="unconfined")
Aug 17 14:03:54 <_my_user_> polkitd(authority=local): Unregistered Authentication Agent for unix-session:3 (system bus name :1.94, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)
Aug 17 14:04:31 <_my_user_> gdm-password]: pam_unix(gdm-password:session): session closed for user <_my_user_>
Aug 17 14:04:31 <_my_user_> systemd-logind[969]: Session 3 logged out. Waiting for processes to exit.
Aug 17 14:04:41 <_my_user_> systemd-logind[969]: Removed session 3.
Aug 17 14:05:01 <_my_user_> CRON[3166501]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 14:05:01 <_my_user_> CRON[3166501]: pam_unix(cron:session): session closed for user root
Aug 17 14:15:01 <_my_user_> CRON[3166529]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 14:15:01 <_my_user_> CRON[3166529]: pam_unix(cron:session): session closed for user root
Aug 17 14:17:01 <_my_user_> CRON[3166534]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 14:17:01 <_my_user_> CRON[3166534]: pam_unix(cron:session): session closed for user root
Aug 17 14:25:01 <_my_user_> CRON[3166554]: pam_unix(cron:session): session opened for user root by (uid=0)
... more of the same ...
Aug 17 15:30:01 <_my_user_> CRON[3166698]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 15:30:01 <_my_user_> CRON[3166698]: pam_unix(cron:session): session closed for user root
Aug 17 15:35:01 <_my_user_> CRON[3166711]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 15:35:01 <_my_user_> CRON[3166711]: pam_unix(cron:session): session closed for user root
Aug 17 15:45:01 <_my_user_> CRON[3166743]: pam_unix(cron:session): session opened for user root by (uid=0)
Aug 17 15:45:01 <_my_user_> CRON[3166743]: pam_unix(cron:session): session closed for user root
Aug 17 15:49:17 <_my_user_> gdm-password]: gkr-pam: unable to locate daemon control file
Aug 17 15:49:17 <_my_user_> gdm-password]: gkr-pam: stashed password to try later in open session
Aug 17 15:49:17 <_my_user_> gdm-password]: pam_unix(gdm-password:session): session opened for user <_my_user_> by (uid=0)
Aug 17 15:49:17 <_my_user_> systemd-logind[969]: New session 2742 of user <_my_user_>.
...
我猜可能是：
Session 3 logged out是系统自动关闭所有打开的图形会话程序并注销的时间New session 2742 of user <_my_user_>是我重新登录时记录的消息（<_my_user_>由于明显的原因被替换）。
这种行为应该归咎于什么？
这种情况并不经常发生，有时我什至让机器在无人看管的情况下运行一天，也没有发生注销。有时它会在一小时内发生。