不再使用sddm的“交换机用户”

Question

我已经进行了广泛的搜索，并且有很多提到这个问题的地方，但是在过去的几个月里，似乎只有几个不同的用户有过这个问题。但是我升级到20.10的3 Kubuntu系统现在都有了它，所以我很惊讶它不是一个已经有解决方案的关键bug。

描述：

• “开关用户”已从K/ Leave菜单中删除
• “开关用户”从SDDM锁定屏幕上消失了(您只能重新输入您自己锁定的会话)。关机/重新启动也会从锁定屏幕上消失。
• 可能与此无关:当注销一些用户(总是相同的用户)时，我会得到一个黑色屏幕(对于其他用户，我会返回一个普通的sddm屏幕，并进行用户选择)。这与kde_settings.conf / MinimumUid问题无关

我们的系统是家庭共享的，所以真的很烦人。如果锁定屏幕是打开的，则必须强制重新启动系统，以便其他用户使用它，同时还涉及到所有磁盘损坏的风险。

这是三种系统之一的结果。我没看到里面有冒烟的枪：

$ journalctl --since "2020-12-25" -u sddm | sed -e "s/.* systemname //"
-- Logs begin at Tue 2019-12-10 19:42:43 CET, end at Sun 2021-01-10 12:09:49 CET. --
systemd[1]: Starting Simple Desktop Display Manager...
systemd[1]: Started Simple Desktop Display Manager.
sddm[2035]: Initializing...
sddm[2035]: Starting...
sddm[2035]: Logind interface found
sddm[2035]: Adding new display on vt 1 ...
sddm[2035]: Loading theme configuration from ""
sddm[2035]: Display server starting...
sddm[2035]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{2eab554e-43ae-4c2b-8751-b3bea3a04ef0} -background none -noreset -displayfd 17 -seat seat0 vt1
sddm[2035]: Setting default cursor
sddm[2035]: Running display setup script  "/usr/share/sddm/scripts/Xsetup"
sddm[2035]: Display server started.
sddm[2035]: Socket server starting...
sddm[2035]: Socket server started.
sddm[2035]: Loading theme configuration from "/usr/share/sddm/themes/ubuntu-theme/theme.conf"
sddm[2035]: Greeter starting...
sddm[2035]: Adding cookie to "/var/run/sddm/{2eab554e-43ae-4c2b-8751-b3bea3a04ef0}"
sddm-helper[2353]: [PAM] Starting...
sddm-helper[2353]: [PAM] Authenticating...
sddm-helper[2353]: [PAM] returning.
sddm-helper[2353]: pam_unix(sddm-greeter:session): session opened for user sddm by (uid=0)
sddm[2035]: Greeter session started successfully
sddm[2035]: Message received from greeter: Connect
sddm[2035]: Message received from greeter: Login
sddm[2035]: Reading from "/usr/share/xsessions/plasma.desktop"
sddm[2035]: Reading from "/usr/share/xsessions/plasma.desktop"
sddm[2035]: Session "plasma.desktop" selected, command: "/usr/bin/startplasma-x11"
sddm-helper[2424]: [PAM] Starting...
sddm-helper[2424]: [PAM] Authenticating...
sddm-helper[2424]: [PAM] Preparing to converse...
sddm-helper[2424]: [PAM] Conversation with 1 messages
sddm-helper[2424]: gkr-pam: unable to locate daemon control file
sddm-helper[2424]: gkr-pam: stashed password to try later in open session
sddm-helper[2424]: [PAM] returning.
sddm-helper[2424]: pam_kwallet5(sddm:auth): (null): pam_sm_authenticate
sddm[2035]: Authenticated successfully
sddm-helper[2424]: pam_kwallet5(sddm:setcred): pam_kwallet5: pam_sm_setcred
sddm-helper[2424]: pam_unix(sddm:session): session opened for user dargaud by (uid=0)
sddm[2035]: Auth: sddm-helper exited successfully
sddm[2035]: Greeter stopped.
sddm-helper[2424]: gkr-pam: gnome-keyring-daemon started properly and unlocked keyring
sddm-helper[2424]: pam_kwallet5(sddm:session): pam_kwallet5: pam_sm_open_session
sddm-helper[2424]: Starting: "/etc/sddm/Xsession \"/usr/bin/startplasma-x11\""
sddm[2035]: Session started
sddm[2035]: Authentication error: "Process crashed"
sddm[2035]: Auth: sddm-helper crashed (exit code 15)
sddm[2035]: Authentication error: "Process crashed"
sddm[2035]: Auth: sddm-helper exited with 15
sddm[2035]: Socket server stopping...
sddm[2035]: Socket server stopped.
sddm[2035]: Display server stopping...
systemd[1]: Stopping Simple Desktop Display Manager...
sddm[2035]: Display server stopped.
sddm[2035]: Running display stop script  "/usr/share/sddm/scripts/Xstop"
sddm[2035]: Removing display ":0" ...
sddm[2035]: Adding new display on vt 1 ...
sddm[2035]: Loading theme configuration from ""
sddm[2035]: Display server starting...
sddm[2035]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{5d343de6-e3c5-4c04-8659-a45f6125ce5f} -background none -noreset -displayfd 18 -seat seat0 vt1
sddm[2035]: Setting default cursor
sddm[2035]: Running display setup script  "/usr/share/sddm/scripts/Xsetup"
sddm[2035]: Display server started.
sddm[2035]: Socket server starting...
sddm[2035]: Socket server started.
sddm[2035]: Loading theme configuration from "/usr/share/sddm/themes/ubuntu-theme/theme.conf"
sddm[2035]: Greeter starting...
sddm[2035]: Adding cookie to "/var/run/sddm/{5d343de6-e3c5-4c04-8659-a45f6125ce5f}"
sddm[2035]: Signal received: SIGTERM
sddm[2035]: Socket server stopping...
sddm[2035]: Socket server stopped.
sddm[2035]: Display server stopping...
sddm-helper[9047]: [PAM] Starting...
sddm-helper[9047]: [PAM] Authenticating...
sddm-helper[9047]: [PAM] returning.
sddm[2035]: Display server stopped.
sddm[2035]: Running display stop script  "/usr/share/sddm/scripts/Xstop"
sddm[2035]: QProcess: Destroyed while process ("/usr/lib/x86_64-linux-gnu/sddm/sddm-helper") is still running.
systemd[1]: sddm.service: Succeeded.
systemd[1]: Stopped Simple Desktop Display Manager.
-- Reboot --
systemd[1]: Starting Simple Desktop Display Manager...
systemd[1]: Started Simple Desktop Display Manager.
sddm[1934]: Initializing...
sddm[1934]: Starting...
sddm[1934]: Logind interface found
sddm[1934]: Adding new display on vt 1 ...
sddm[1934]: Loading theme configuration from ""
sddm[1934]: Display server starting...
sddm[1934]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{d57df6b7-2776-4dc6-b28b-1746e9a6613d} -background none -noreset -displayfd 17 -seat seat0 vt1
sddm[1934]: Setting default cursor
sddm[1934]: Running display setup script  "/usr/share/sddm/scripts/Xsetup"
sddm[1934]: Display server started.
sddm[1934]: Socket server starting...
sddm[1934]: Socket server started.
sddm[1934]: Loading theme configuration from "/usr/share/sddm/themes/ubuntu-theme/theme.conf"
sddm[1934]: Greeter starting...
sddm[1934]: Adding cookie to "/var/run/sddm/{d57df6b7-2776-4dc6-b28b-1746e9a6613d}"
sddm-helper[2206]: [PAM] Starting...
sddm-helper[2206]: [PAM] Authenticating...
sddm-helper[2206]: [PAM] returning.
sddm-helper[2206]: pam_unix(sddm-greeter:session): session opened for user sddm by (uid=0)
sddm[1934]: Greeter session started successfully
sddm[1934]: Message received from greeter: Connect
sddm[1934]: Message received from greeter: Login
sddm[1934]: Reading from "/usr/share/xsessions/plasma.desktop"
sddm[1934]: Reading from "/usr/share/xsessions/plasma.desktop"
sddm[1934]: Session "plasma.desktop" selected, command: "/usr/bin/startplasma-x11"
sddm-helper[2276]: [PAM] Starting...
sddm-helper[2276]: [PAM] Authenticating...
sddm-helper[2276]: [PAM] Preparing to converse...
sddm-helper[2276]: [PAM] Conversation with 1 messages
sddm-helper[2276]: gkr-pam: unable to locate daemon control file
sddm-helper[2276]: gkr-pam: stashed password to try later in open session
sddm-helper[2276]: [PAM] returning.
sddm-helper[2276]: pam_kwallet5(sddm:auth): (null): pam_sm_authenticate
sddm[1934]: Authenticated successfully
sddm-helper[2276]: pam_kwallet5(sddm:setcred): pam_kwallet5: pam_sm_setcred
sddm-helper[2276]: pam_unix(sddm:session): session opened for user dargaud by (uid=0)
sddm[1934]: Auth: sddm-helper exited successfully
sddm[1934]: Greeter stopped.
sddm-helper[2276]: gkr-pam: gnome-keyring-daemon started properly and unlocked keyring
sddm-helper[2276]: pam_kwallet5(sddm:session): pam_kwallet5: pam_sm_open_session
sddm-helper[2276]: Starting: "/etc/sddm/Xsession \"/usr/bin/startplasma-x11\""
sddm[1934]: Session started
systemd[1]: Stopping Simple Desktop Display Manager...
sddm[1934]: Signal received: SIGTERM
sddm[1934]: Authentication error: "Process crashed"
sddm[1934]: Auth: sddm-helper crashed (exit code 15)
sddm[1934]: Authentication error: "Process crashed"
sddm[1934]: Auth: sddm-helper exited with 15
sddm[1934]: Socket server stopping...
sddm[1934]: Socket server stopped.
sddm[1934]: Display server stopping...
sddm[1934]: Display server stopped.
sddm[1934]: Running display stop script  "/usr/share/sddm/scripts/Xstop"
sddm[1934]: Removing display ":0" ...
sddm[1934]: Adding new display on vt 1 ...
sddm[1934]: Loading theme configuration from ""
sddm[1934]: Display server starting...
sddm[1934]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{784e9002-ceaa-453f-9bbe-8c596e312df0} -background none -noreset -displayfd 18 -seat seat0 vt1
sddm[1934]: Failed to read display number from pipe
sddm[1934]: Display server failed to start. Exiting
systemd[1]: sddm.service: Main process exited, code=killed, status=6/ABRT
systemd[1]: sddm.service: Failed with result 'signal'.
systemd[1]: Stopped Simple Desktop Display Manager.
systemd[1]: sddm.service: Triggering OnFailure= dependencies.
systemd[1]: sddm.service: Failed to enqueue OnFailure= job, ignoring: Transaction for plymouth-quit.service/start is destructive (systemd-tmpfiles-setup-dev.service has 'stop' job queued, but 'start' is included in transaction).
-- Reboot --
systemd[1]: Starting Simple Desktop Display Manager...
systemd[1]: Started Simple Desktop Display Manager.
sddm[2066]: Initializing...
sddm[2066]: Starting...
sddm[2066]: Logind interface found
sddm[2066]: Adding new display on vt 1 ...
sddm[2066]: Loading theme configuration from ""
sddm[2066]: Display server starting...
sddm[2066]: Running: /usr/bin/X -nolisten tcp -auth /var/run/sddm/{f4e5de63-9bec-4555-b1c8-b622830fff8f} -background none -noreset -displayfd 17 -seat seat0 vt1
sddm[2066]: Setting default cursor
sddm[2066]: Running display setup script  "/usr/share/sddm/scripts/Xsetup"
sddm[2066]: Display server started.
sddm[2066]: Socket server starting...
sddm[2066]: Socket server started.
sddm[2066]: Loading theme configuration from "/usr/share/sddm/themes/ubuntu-theme/theme.conf"
sddm[2066]: Greeter starting...
sddm[2066]: Adding cookie to "/var/run/sddm/{f4e5de63-9bec-4555-b1c8-b622830fff8f}"
sddm-helper[2344]: [PAM] Starting...
sddm-helper[2344]: [PAM] Authenticating...
sddm-helper[2344]: [PAM] returning.
sddm-helper[2344]: pam_unix(sddm-greeter:session): session opened for user sddm by (uid=0)
sddm[2066]: Greeter session started successfully
sddm[2066]: Message received from greeter: Connect
sddm[2066]: Message received from greeter: Login
sddm[2066]: Reading from "/usr/share/xsessions/plasma.desktop"
sddm[2066]: Reading from "/usr/share/xsessions/plasma.desktop"
sddm[2066]: Session "plasma.desktop" selected, command: "/usr/bin/startplasma-x11"
sddm-helper[2414]: [PAM] Starting...
sddm-helper[2414]: [PAM] Authenticating...
sddm-helper[2414]: [PAM] Preparing to converse...
sddm-helper[2414]: [PAM] Conversation with 1 messages
sddm-helper[2414]: gkr-pam: unable to locate daemon control file
sddm-helper[2414]: gkr-pam: stashed password to try later in open session
sddm-helper[2414]: [PAM] returning.
sddm-helper[2414]: pam_kwallet5(sddm:auth): (null): pam_sm_authenticate
sddm[2066]: Authenticated successfully
sddm-helper[2414]: pam_kwallet5(sddm:setcred): pam_kwallet5: pam_sm_setcred
sddm-helper[2414]: pam_unix(sddm:session): session opened for user dargaud by (uid=0)
sddm[2066]: Auth: sddm-helper exited successfully
sddm[2066]: Greeter stopped.
sddm-helper[2414]: gkr-pam: gnome-keyring-daemon started properly and unlocked keyring
sddm-helper[2414]: pam_kwallet5(sddm:session): pam_kwallet5: pam_sm_open_session
sddm-helper[2414]: Starting: "/etc/sddm/Xsession \"/usr/bin/startplasma-x11\""
sddm[2066]: Session started

2021年更新:升级到kubuntu 21.10之后，它终于按预期运行了几个星期.直到有人把它搞砸了。现在，使用开关用户选项将导致一个无法恢复的黑色屏幕。我仍然可以使用Ctrl-Alt-F2来杀死和重新启动等离子体，但这是不好的。当我有时间收集数据的时候会发布更多。

Answer 1

在我的经验中，最简单的解决方法(直到21.04出炉)是Ctrl-Alt-F2 (F3，F4，.)，以控制台模式登录并键入startx。

Answer 2

Systemd不再提供"CanMultiSession“属性，因此使用该属性的软件现在中断:(

KDE在5.20.3中修正了这一点

请参阅：https://bugs.kde.org/show_bug.cgi?id=427777

Answer 3

在我看来，对于默认的Kubuntu等离子桌面来说，似乎是一个主要的主题缺陷，我找不到一个明确的解决方案。

这是我的解决办法：

将“用户开关”小部件添加到桌面：

右击桌面上的一个空点，从菜单中选择'Add‘。在搜索栏中键入“user”。把它添加到桌面上。

更改默认登录屏幕：

应用程序启动程序->系统设置->启动和Shutdown+Login屏幕

我选择‘获取新登录屏幕’，并选择了一个有一个下拉菜单为用户。在我的例子中，它是一个叫做“糖糖”的屏幕。

我在这个解决方法中遇到了一些问题：

锁定会话只允许锁定的用户登录。要切换用户，需要当前用户重新登录，然后使用开关用户小部件。

如果当前用户启动了一个新会话，它将在tty2上启动一个不可用的会话。一度陷入困境，不得不重新启动。在大多数情况下，可以离开新的会话'Ctrl+Alt+F1‘。

这是在我的Kubuntu 20.04测试。一个新的Kubuntu 20.10在一个VM。在20.04的某个时候，一个“交换机用户”图标突然出现在应用程序启动程序中，这是以前没有的。还是不知道是什么原因造成的。

我将与其他发行版一起探讨KDE，以确定这是Kubuntu问题还是KDE问题。

我的意见是：

对于一台多用户的机器来说，这将是一个明确的交易破坏者。我多年来一直使用Kubuntu作为唯一的用户，并且非常喜欢它。但是对于多个用户，我觉得这将是完全垃圾与当前的默认安装。