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Here is my incrontab (tony's incrontab):

/home/tony/Workspace/cocoonr/ui/static/ui/img/icons/vector IN_MODIFY,IN_CREATE,IN_MOVED_TO /bin/sh /home/tony/Workspace/cocoonr/boilerplate/svg2djangohtml $@/$# /home/tony/Workspace/cocoonr/ui/templates/inc/icons/

I tested it multiple times changing some things, no way to make it work when incrond is run as a service (using openrc).

If I run incrond in foreground (incrond -n), then tony's incrontab works

If I set root's incrontab to the one given above, it works even when run as a service.

My tony is in /etc/incron.allow:

root
tony

And there is no /etc/incron.deny.

I even tried with a much simpler incrontab:

/tmp/foo IN_ATTRIB touch /tmp/bar

The results are the same.

How to make user's incrontab working?

Antoine Pinsard
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2 Answers2

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If the binary for incrontab (which I don't know, never used it) hasn't his SGID bit set, that could cause this type of strange behaviour.

Set it with chmod g+s /path/to/binary (/usr/bin/incrontab, maybe?)

You can assess if it's set by:

ls -l /path/to/binary

(example)

ls -l /usr/bin/crontab
-rwxr-s--x 1 root crontab 44336 Jun 23 18:47 /usr/bin/crontab
Rafael Umbelino
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    This does not work. :/ – Antoine Pinsard Jun 29 '16 at 17:47
  • incrontab has no binary? SGID bit was already set? What was the situation? – Rafael Umbelino Jun 29 '16 at 17:48
  • /usr/bin/incrontab has SUID set. Owner is `root`, group is `root`. I tried to set SGID but it didn't work either. – Antoine Pinsard Jun 29 '16 at 17:49
  • Now that's strange. incrontab should run as root regardless of the user trying to execute it. But maybe we are onto something here. Group is root, right? Change it to crontab, set SGID bit and try again. Let's dig this one out. – Rafael Umbelino Jun 29 '16 at 18:18
  • I can't see the point in setting group `crontab`. incrontab is not related to crontab. Could you please explain the idea behind this? – Antoine Pinsard Jun 29 '16 at 18:22
  • Just a hunch based on the fact that I hit almost the same situation with another application that didn't work if I called as normal user, but worked fine as root. I had to change the binary's group to video so it could output to video. Go figure that one. – Rafael Umbelino Jun 29 '16 at 18:25
  • This doesn't change anything either. But anyway, the issue should not be about calling the `incrontab` executable. The daemon executes the commands as the same user whether it is root's incrontab or a user incrontab. And I think it reads it directly from files in `/var/spool/incron/` rather than through the `incrontab` command. – Antoine Pinsard Jun 29 '16 at 18:33
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I faced a similar issue (that's how I found this question).

If the following command makes it work,

incrontab -n

the issue might be that the incron/incrond service isn't running. Check if it is running and whether it is enabled to run on boot (in case the system is restarted).

The other issue I was facing was because of an infinite loop I had inadvertently created.
If your script modifies any file in the very folder incron is watching, it keeps triggering events and each event causes a new process (via fork()). Soon, the service can't fork any more. The service log shows the following error in this case.

cannot fork process: resource temporarily unavailable

At this point,

  • stop the service
  • change the script so it doesn't modify files within the watched folder
  • restart the service
G-Man Says 'Reinstate Monica'
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Robin Parriath
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