Am Thursday, 5. November 2009 schrieb RalfGesellensetter: > Please follow recent IRC log on #debian-edu to find some alternative > approaches on clearing left-behind processes deliberately (rather > than killing arbitrary unidentified processes).
Dear list, only now I find the time to sumarize some thoughts from IRC: <RalfG> h01ger: I start to understand what you dislike about killer. It kills processes not on purpose, but arbitrary -- like a redneck (alternative package name?) shooting at everything that doesn't match his patterns. <RalfG> I tend to agree that this approach is "bad" as it must fail as soon as you introduce new roles unknown to killer. <RalfG> On contrary, the clean-up-left-behind-processes-after-logout- script should follow a simple and clean policy like this: <RalfG> get a list of users who were logged in today - and if they aren't logged in anymore, kill _their_ processes. <RalfG> all needed for this can be found (again) in last. <RalfG> alternatively, you could follow /var/log/auth.log and wait for "logout" messages. But this log is on tjener, I think. <RalfG> Yet another approach could be to have processes of users killed, that are member in a given group (student) unless they are still logged in. <RalfG> h01ger: this command shows all user sessions that have been closed today: grep "session closed" /var/log/auth.log |grep -v "user root" | grep -v \ "user daemon" | grep -v "user nobody" |grep "`LANG=C date +"%b %_d"`" \|cut "-d " -f12 |sort -u | grep ... | tr '[A-Z]' '[a-z]' <RalfG> Now find users who are still logged in: LANG=C last |grep "still logged in" | cut "-d " -f1 | sort -u <RalfG> note: here might be ambigious names as logins are truncated to 8 characters. <RalfG> Now I could do a "grep -v" on every line there to remove still logged in users... <RalfG> rather than triggering the clean-up-left-behind-processes-after- logout-script every hour, wouldn't it be great just to write a watchdog for auth.log - something like "tail -f /var/log/auth.log" that issues a pkill whenever a (regular) user closes their sessioN? <RalfG> of course, this would mean, that all processes are killed of one of several sessions owned by the same user is closed (unless doublechecking "who"). <RalfG> and, of course, this script should not regard old entries in auth.log in case it is started much after boot time Now, I think a combination of both should be possible (do the filtering on tail -f) -- and yes, of course, users who are permanently logged in will not be regarded (maybe by nightkill in debian-edu-config?). There was also a discussion that virtually the session manager (like LDM) should do the job in a propper way, but then, there is also KDM and GDM, and it is hard to convince their upstreams to find a common way of purging closed sessions. Hence the watchdog for auth.log seems to be a straight forward way to go (to me), what do you think? First steps could be auxialary scripts like test-if-user-is-logged-in (checking in who). Then I wonder, if there isn't a mother process to all processes run within a session, so that the only thing to do is killing this embedding process at logout time? -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
