#374 breaks tmux

[yan12125]

Expected Behavior

tmux server created inside LXQt persists after logging out and can be attached later

Current Behavior

Since #374, the tmux server is gone upon logging out

Possible Solution

• A whitelist for procceses that should not be killed? See comments at session: Become subreaper & end children upon finish #374 for previous discussions.
• Check how other desktop environments work?

Steps to Reproduce (for bugs)

1. Run qterminal from within LXQt (click the quicklaunch button in my case)
2. Run tmux
3. Detach the tmux session. Now the tmux server is a sub-process of lxqt-session. Here are partial outputs of pstree:

        │                        └─lxqt-session─┬─
        │                                       ├─tmux: server───zsh

4. Log out of the LXQt session

Context

I wanted to observe how proccese are killed #374 by running journalctl --follow in tmux.

System Information

• Distribution & Version: Arch Linux
• Kernel: 5.10.28
• Qt Version: 5.15
• liblxqt Version: git
• lxqt-build-tools Version: git
• Package version: git

[tsujan]

Check how other desktop environments work?

I think other DEs may do nothing, other than stopping some of their own processes. I've seen Gnome/KDE processes that persisted after logging out of them (and took lots of CPU time until I killed them in LXQt). That's not what we want.

IMHO, #374 is an elegant and clean solution. A list that can be edited/provided by the user and also a few hard-coded exceptions might solve this problem.

[stefonarch]

I think starting processes that are thought to survive the session is a dev-only thing - an average user doesn't do it.

[palinek]

We have few options here I can imagine now:

1. create a specific whitelist/regexp configuration of app names in session configuration
2. in lxqt-session examine some flag of the process (easiest way for linux would be to examine env. vars of the process and in case some well defined variable exists...let the process alone; the drawback here is, that in BSD I don't know about the possibility to examine env. vars of other/child process)
3. in lxqt-session check the "well-defined" env. var for whitelist/regexp app names (most easy portable implementation - configuration of env. vars for session is done; but a bit hidden for the end user)

For now the easiest way is to let the "parent" process of "need to live" process to be alive and that should ignore the TERM signal -> then our "need to live" process will survive, e.g.:

#/bin/bash
trap 'DUMMY=1' TERM

# start the requested process
"$@"