Maintain the system ¶

Update the system from time to time ¶

Keeping the system updated is important for security and stability. I recommend running the following commands on each server at least once a month, or whenever you receive security update notifications.

sudo dnf update -y

Caution

If the server has NVIDIA drivers installed, please note whether the update includes NVIDIA driver updates, as these breaks the driver immediately and require a system reboot.

Reboot the system if necessary ¶

If the update includes kernel updates or NVIDIA driver updates, please reboot the system as soon as possible to apply the updates.

Before rebooting, please check if there are any active users on the system and inform them about the reboot. It is not an easy job. The next section describes how to check active users and their sessions.

Please announce the reboot in advance in our Slack channel. Good communication is important to avoid unnecessary disruption to users.

Check who has running sessions ¶

Active users only ¶

w is just more verbose than who, they:

Does not show background processes (tmux, screen, cron, daemons)
Includes sessions that are technically active or “connected”
Inactive GUI sessions may appear as display manager keeps the session alive

Check what a user is running in a session ¶

If a session is closing, most likely it is because of tmux or screen. Check what is holding the session: (Use sudo if it is not your own session)

sid=<SESSION_ID>
uid=$(loginctl show-session $sid -p User --value)
scope=$(loginctl show-session $sid -p Scope --value)
systemd-cgls /sys/fs/cgroup/user.slice/user-$uid.slice/$scope

Warning

Dangerous command alert: Do not kill any process without checking what it is. If you are not sure, ask for help in our Slack channel.

loginctl terminate-session $sid
# If refuses, it will not kill if tmux is there.
loginctl kill-ssession <SESSION_ID> -s SIGKILL
# Then you need to kill tmux / screen using PID
kill <PID> <PID> ...
# add -9 to force it
kill -9 <PID>

Check what a user is running in all sessions ¶

uid=148600005
sudo systemd-cgls /user.slice/user-$uid.slice/
# If you need ground truth
sudo ps -u $uid -o pid,ppid,tty,stat,cmd

Problem service: systemd-logind

systemctl restart systemd-logind

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