Using Slackware64-current with recent updates, Xfce-4.14, login via xdm into xfce4 session, no KDE.

Every time I log in, ssh-agent starts. It does not stop when I log out. The number of ssh-agents currently running, as well as the number of /tmp/ssh-* directories, equals the number of times I have logged in since boot-up.

It looks like xfce4-session starts these up, but they are not exiting at logout like they should, for some reason.

I found that I can disable ssh-agent startup at login with this:

Or re-enable it with this:
I disabled it, since I don't seem to need it. But does anyone know why it isn't stopping at logout?

Yep, I tried launching Xfce using startx and then logging out. The ssh-agent is not stopped here too. Maybe it's a normal behaviour? Since the ssh-agent is reparented to PID 1 (init) so the main Xfce process doesn't know its PID to be able to stop it properly at logout.

Interestingly, running
in the terminal emulator inside Xfce prints out the PID of the started ssh-agent, which means that environment variable is already set and accessible by processes started by the user. I don't know why the main Xfce process doesn't use that environment variable to kill the started ssh-agent when the user logs out.

Probably not really helpful, just giving my thoughts.

Thanks for your reply and checking on it. I did take a look at the xfce4-session source code, and found that there is a function for shutting down the session that kills off ssh-agent. But as far as I can tell it never gets called. I put some tracing print calls in there, and they never appeared; I searched the source code and found no place that calls it (xfsm_startup_shutdown()). The next step would be to open a bug on the xfce4-session tracker... I'm thinking about it.

As far as I understand, $SSH_AGENT_PID allows processes in your login session to communicate with the ssh-agent. Once you log out, the still-running ssh-agent is probably inaccessible because no process still has its PID in $SSH_AGENT_PID. Which makes the extra ones useless.

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I think that should be $SSH_AUTH_SOCK, the path to the running ssh-agent's socket file. In KDE Plasma, I usually use $SSH_AGENT_PID to kill ssh-agent when logging out by putting "kill $SSH_AGENT_PID" in a shutdown script and put that script in $XDG_CONFIG_HOME/plasma-workspace/shutdown. Although after I was able to emulate systemd's user-level services functionality that start/stop user's services at user's login/logout using s6 + s6-rc together with elogind DBus interface, I just added ssh-agent to the list of services that should be started when I login and then deleted that shutdown script since it's not needed any more .