I would like to know how to stop the system from rebooting after running a yum update.
I use a script on each system which runs daily yum updates through cron and if an uodate is critical enough (for example a new kernel version) it will check whether any users are logged in and whether some specific software is running which should postpone a reboot. If this is not the case it will schedule a reboot.
However this does not appear to work very well (anymore). The system will reboot regardless, after a few minutes when a yum update ran by hand or by my script has finished. I need to know which mechanism is used to schedule this reboot and how to control it. There are many systems, such as those running simulations for weeks, that I prefer not to have rebooted. For those systems propagating a critical kernel fix is less important than keeping it up and running. I tried to find information but was unable to yet.
I did check the cronjobs as one of the first possible causes but was unable to find anything suspect. In addition when the uodate script's cronjob is enabled and I run yum update by hand the system will still reboot after a few minutes when the update has finished. Yum also does not appear some custom installed "warapper" script.
Edit: Problem was that even though the cronjob to run updates was disabled by me the package which contains the script and cronjob entry was updated as well, as a result it would reinstall the cronjob and cause the script to run and a reboot to occur. Fixing the script...
This is behavior that your organization has added - it's not behavior controlled by packaged scripts. Your best bet in finding out what causes the reboots is by asking within your organization. Those of us outside your organization can be of only marginal help.
Having said that, I would start by checking the scripts in
/etc/cron.daily/,/etc/cron.d/and any old-style cron jobs (crontab -l).