Systemd Linger

# Summary Systemd's "linger" feature allows user processes to continue running after logout, though it's widely misconceived as necessary for screen/tmux functionality—on Debian systems with default settings, these tools work fine without it. The KillUserProcesses option can be enabled to terminate user processes at logout, which helps manage misbehaving services like KDE components without requiring a reboot. Users can control linger status with loginctl commands, though checking if linger is enabled requires manually inspecting the `/var/lib/systemd/linger` directory.