I'm logging in to a system via SSH and I'd like to be able to force a command to be run on logout, whether that's an intentional logout (exiting the shell) or because my SSH connection has dropped/been terminated. Is there any way to set this up? My best guess right now is to change the login shell to a program that intercepts the signal sent on SSH closing (SIGHUP?) and executes the command then, but I'm wondering if there's a cleaner solution.
The best way to do this would be to use pam.
/etc/pam.d you will have several files, one of them will be called
sshd. If you only want to affect ssh, and not other logins (such as a GUI, or real TTY), you want this file.
If you want to affect all logins, you'll want a 'common' file. The name of this other 'common' file varies by distro, but you can track it down by following the
substack statements in the
sshd file until you get to the base file.
Once you've identified the file in
/etc/pam.d that you want to use, add a line such as the following to the
session optional pam_exec.so quiet /etc/pam_session.sh
This will result in calling
/etc/pam_session.sh every time someone logs in and logs out (whether gracefully or ungracefully).
Now you just need to create
/etc/pam_session.sh. Below is an example you could use to run something every time someone logs out:
#!/bin/sh if [ "$PAM_TYPE" = "close_session" ]; then something fi
(don't forget to
chmod a+x the script)