thinkgeek

I am writting a daemon in python which should start at system start up with all inet.d services
on an NIS server. Then it should listen to any user login and then start a new process for that user on his login which will continue throughout his entire session.

Can anyone give any help or any suggestion or any useful links.

thinkgeek

Cerulean

Well which part do you need help with? Just doing so in general? If so, that's quite a specialized thing you're trying to do... you're probably better off asking someone with a more extensive collection of information on these kind of things.

thinkgeek

I want my daemon to start at system start up as other (start|stop|restart) services/daemons. It work is to listen to user logins. Whenever a user logins at the terminal(local or NIS client) it should get the username. It will start a new thread which will run throughout the session of that user. This should be done for any user who logs in. But I want my daemon to be smart enough to know immediately who is login into the system, so that it can respond accordingly.

Moldz

What *nix are you using? FreeBSD is very different from RedHat which is different than Gentoo. They all involve creating some type of script.

I'm not sure how you would do that. You could make it work similar to the "who" program by simply rechecking the /var/run/utmp for new entries.

thinkgeek

1. I am using Redhat Enterprise Linux

2. Could you explain how to get username from /var/run/utmp.
It is in some different format which can't be understood.

Moldz

Ok then, check out /etc/init.d, it is full of scripts that start programs on boot. They are somewhat simple bash scripts, I would make a copy of one of them and change what you need. Then use the program /sbin/chkconfig to setup the script to run on boot

The utmp file is in a binary format. You can find out the exact structure by checking out the man page, "man utmp".

Cerulean

Alternatively you can spawn a new who process every few seconds and read its output. That would be easier than parsing /var/run/utmp, but you'd get a performance hit for spawning a new process so often - i'd go with the file parsing option myself.

thinkgeek

Could you explain how to parse the /var/run/utmp file. It is in binary format.

TheFalseDragon

couldn't you just have a program that when someone logs in autoruns telling this program that they have logged in? wouldn't that be much simpler....

Cerulean

I'd assume not, as this daemon wants to log all logins, so i'd assume it needs root powers (e.g it will write to certain files or do certain things that require root access). Giving each user access to the data this daemon will work with would not strike me as safe.

As was said, read through the manpage for utmp. It's perfectly documented there.