I'm hosting an experimental/testing Linux box, running Debian Wheezy 7.4.0 distribution. Different users log into the machine over ssh to their accounts and are allowed to run the development tools and leave their programs running as services in background if they so wish.
Since this is a testing machine for all kinds of purposes there is often a need to restart the whole machine and then the users have to log back in and restart their user-space stuff that was running. I would like to automate that. Basically I would like to provide the users with a mean to launch stuff right after the machine boots up(after everything else is initialized) and a mean to launch stuff upon system shutdown(with no time limitations, basically stalling the shutdown until all those shutdown user processes have completed).
What I have tried so far:
I've created an init bash script, by following the principles found in the 'skeleton' template file under /etc/init.d/ (Skeleton template source code: https://gist.github.com/ivankovacevic/9917139)
My code is here: https://github.com/ivankovacevic/userspaceServices
Basically the script goes through users home directories and looks for executable files in corresponding subdirectories named .startUp, .shutDown or .status. Depending on the event that is currently going on the scripts get executed with su as if the users have started them themselves.
The problem I'm currently facing with this approach is that there is a strange process left hanging after the system boots and the script starts all the processes of other users. This is how it looks in the processes list:
UID PID PPID C SZ RSS PSR STIME TTY TIME CMD root 3053 1 0 1024 620 1 17:42 ? 00:00:00 startpar -f -- userspaceServices
I don't know what that process is and man page for it does not mention the -f argument. So I'm clueless but I must be doing something wrong since no other script/service from init.d leaves such a process hanging after boot.
So I'm looking for someone to help me debug this solution I have(which also seems a bit complex in my opinion). Or give me some idea how this could be implemented in an entirely different way.
I've started a separate question for the startpar issue: startpar process left hanging when starting processes from rc.local or init.d
Problem solved for my original solution. Check the previously mentioned question for startpar. The code on GitHub is also corrected to reflect that.
UPDATE 3 - How to use crontab
As Jenny suggested, regular users can schedule tasks to be executed once upon boot using crontab. I find that to be the easiest method, if all you need is starting user tasks on boot and not shutdown. However there is a drawback that users can leave cron process "hanging" as parent when they launch on-going, service-like tasks. First let me just explain how it works:
regular users themselves should call:
( -e as in edit ) Which opens a default console text editor with their user crontab file. To add a task to be executed at boot, a user must add one line at the end of the file:
Now if the user would do just that and if that file is not just some simple script that linearly completes something and ends, but some sort of watchdog for example, after a reboot you would end with something like this in your processes list:
1 2661 root 20 0 20380 860 660 S 0.0 0.0 0:00.00 ├─ /usr/sbin/cron 2661 2701 root 20 0 33072 1152 868 S 0.0 0.0 0:00.00 │ └─ /USR/SBIN/CRON 2701 2944 someuser 20 0 4180 580 484 S 0.0 0.0 0:00.00 │ └─ /bin/sh -c ./watchdog 2944 2945 someuser 20 0 10752 1204 1016 S 0.0 0.0 0:00.00 │ └─ /bin/bash ./watchdog 2945 2946 someuser 20 0 23696 4460 2064 S 0.0 0.1 0:00.01 │ └─ /usr/bin/python ./some_program.py
To avoid that the user needs to modify his crontab entry to look like this:
@reboot /path/to/the/executable/file >/dev/null 2>&1 &
The redirections of file descriptors are optional but recommended to keep it clean. If you want to study why, try looking at them:
ls -l /proc/pid_of_started_process/fd