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Nagios is a IT infrastructure monitoring system. I am writing a simple plug-in script for it. A special account, nagios, has been created for it, and the script gets run by Nagios under that account.

For debugging purposes, the script is very simple:

#!/bin/bash
echo "OK - Running okay" ~ `id`

It echoes the value of ~, i.e. the home directory, and the result of the id command.

I log into the nagios account (su -l nagios), and test it from the command line:

OK - Running okay /home/nagios uid=1005(nagios) gid=1007(nagios) groups=1007(nagios),1008(nagcmd)

That is exactly what I expect.

I run it from within the Nagios system, the reported results are:

OK - Running okay /home/julian uid=1005(nagios) gid=1007(nagios) groups=1007(nagios),1008(nagcmd)

Wait, /home/julian is my account's home directory; but it is logged into the nagios account. That contradiction makes no sense to me; I obviously don't understand how this is meant to work.

Any suggestions how this might be happening?

Oddthinking
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2 Answers2

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Is your script ran by sudo by any chance?

rpinson@rpinson:~$ echo ~; id
/home/rpinson
uid=61367(rpinson) gid=100(users) groupes=24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),100(users),119(admin)
rpinson@rpinson:~$ sudo -u toto -s
toto@rpinson:~$ echo ~; id
/home/rpinson
uid=1001(toto) gid=1001(toto) groupes=1001(toto)

In some cases (like sudo -u), the environment is exported so $HOME is not resetted for the user executing the command.

In the case of sudo, there are ways of using the user's environment:

rpinson@rpinson:~$ sudo -u toto -i
toto@rpinson:~$ echo ~; id
/home/toto
uid=1001(toto) gid=1001(toto) groupes=1001(toto)

or

rpinson@rpinson:~$ sudo -u toto -H -s
toto@rpinson:/home/rpinson$ echo ~; id
/home/toto
uid=1001(toto) gid=1001(toto) groupes=1001(toto)
raphink
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  • That is very interesting. I don't have an answer for you. I assumed that Nagios was running under the user nagios and simply spawning a process, not using sudo, but that's beneath the covers. – Oddthinking Feb 13 '11 at 06:54
  • My problem is solved (inspired by this, I just specified an explicit path rather than referencing ~, and my other issues vanished. I've decided to accept this answer as the best. – Oddthinking Feb 13 '11 at 06:56
  • Great, glad it answers your question :-) – raphink Feb 13 '11 at 17:57
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Nagios is calling into a remote system so probably you are running the script through ssh julian@remote.

SpliFF
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  • I am connecting via ssh julian@remote to a server. Nagios is running on the server (hopefully as nagios), and is calling the local script. When it runs the local script, `id` is reporting that it is running as nagios. It is just `~` that reports /home/julian. – Oddthinking Feb 11 '11 at 04:06