AIX

Hi All,

May be a dumb question to old AIX hacks, if so apologize.
I have worked with /etc/inittab on SCO, but apparently with AIX you should use the 'mkitab' command to add entries instead of just vi'ing the file.

I just need a daemon process (script called 'dpr_daemon') to kick off once and restart if it is ever killed.
After checking through documentation, the logical step appears to be (level 2, normal) add to inittab w/this line:


mkitab "dprdaemon:2:respawn:/dplogs/dpr_daemon"

However, when I do this, I immediately find 10-25 dpr_daemons running on the box. The shock and awe result. Live box, can't play around too much with this.

Is there something I am missing? Surely 'respawn' is as documented in man pages, respawn the process only if killed. 'once' would not restart the process if killed.

Thanks much for any advice---
jpass

The syntax is correct, but it seems init thinks that process is already dead and spawns a new one. If I find anything about it, I will post it.

Someone mentioned that perhaps since this program runs in the background, that inittab thinks the program has ended and keeps respawning again and again.

But I don't know how to write a daemon that runs in the foreground. Is there such a thing? Then it would become a program, and no longer be a daemon anymore.
Not sure, dont' completely understand.

I think the thing you need to ask is does the script run continuously or does it naturally finish (die). If it does in fact finish then it will respawn. What does the script do?

I don't know SCO. As an AIX admin I'd probably create a subsystem and put it under control of the AIX System Resource Controler SRC. Start with the mkssys man page if that was an option.
However, if you want to stick to your setup - what if your script would check itself whether it is already running so that it would refrain from starting again while it is active?

I would have to assume then that the command for doing this (in my instance) would be:

mkssys -p /dplogs/dpr_daemon -s dprdaemon -u 0 -a "-D" -e /dev/null -i /dev/null -o /dev/null -R -S -f 9 -n 15

you would then:

startsrc -s dprdaemon
stopsrc -s dprdaemon

To start and stop the process, and it would automatically restart if killed.

I have seen examples with a "-G tcpip" tacked on the end, but since this new little daemon is I assume not related to any group, I would think that would not be included.

I don't completely understand the references to /dev/null here but does anyone see any holes here? I assume this would make it permanent? I really don't have the option of shutting down/rebooting the box.
Just looking for help, thanks!

jeffpas

When a daemon (such as init) runs a subprocess, it is also a daemon. No need to do anything else.

Let's say that init spawns process 1234 for your program. Now init expects pid 1234 to stay around. If it exits, init will respawn it. This is why your program must not try to redaemonize itself. That involves spawning a child and then exiting. init will not recognize the child of pid 1234 as a replacement. Pid 1234 died, so init thinks it needs another copy.