in reply to Re^2: Running a perl script automatically on Mac OS X 10.5
in thread Running a perl script automatically on Mac OS X 10.5

Hi, I don't know much about OS X, but some OS have additional security restrictions. E.g., your UID might need to be listed in /etc/cron.allow and not in /etc/cron.deny (ALL matches every user) to be eligible to execute cronjobs.

Usually cronjobs are executed under plain /bin/sh, so you might explicitly want to change that. Furthermore, I would not trust tilde expansion. It might work, but using $HOME/path/to/script.pl or even manually expanding ~/ might help here. Most cron systems allow to set SHELL and HOME in the cronjob file.

Perl should be in your $PATH, but expanding that to /usr/bin/perl - or wherever perl is installed on your system is more reliable and secure. If your script.pl accesses some non-standard environment variables (i.e., via %ENV) you might need to explicitly start your standard shell (see: /etc/passwd) or use a wrapper.

So, you might end up with: 23 13 * * * /usr/bin/perl -w /home/prince9/path/to/script.pl
where /home/prince9 is the output of echo ~ and /usr/bin/perl is hopefully the output of type perl ... have a look at e.g. /var/log/messages too...

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Re^4: Running a perl script automatically on Mac OS X 10.5
by Ninth Prince (Acolyte) on Sep 09, 2008 at 13:44 UTC

    Had to go away for a few days. Okay, so here is what I have done. In my cron.txt file I now have the line 21 08 * * * /usr/bin/perl -w /Users/myname/Documents/path/to/CronTest.pl. I copied that "sixth variable" part (the part starting with /usr and all the way through /CronTest.pl) to the command line in my Terminal window and the script executed fine, so I know that command part of the cron listing is correct. (BTW, what is that "sixth variable" called? In my mind I'm calling it the command, but am not sure if this is correct.)

    It was 8:19 a.m. when I saved the cron.txt file and still 8:19 when I entered crontab cron.txt. I checked crontab by entering crontab -l and it appeared to be correct. When 8:21 rolled around, however, nothing happened.

    If you think this is a security issue, could you be a bit more specific about what I might have to do (My exposure to UNIX is limited and occurred about 15 years ago.)

    If not a security issue, what might I be doing wrong?

    Thanks for your help!

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      you are not checking error logs/messages
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        How do I do that?

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      Right, my man pages call the sixth argument command, it's the whole thing /usr/bin/perl -w /Users/.../CronTest.pl.

      First, please check /var/log/messages or /var/log/warn (maybe there is someting in /var/adm/ too, it depends on the OS) if something suspicious happened around 08:19-08:21. It is AFIK important that your crontab file ends with a linefeed but not with an empty line! So please check that too.

      How does your Perl program displays that it has done something? Does it create a file or a log-entry? Do not expect to see something in your terminal or in your X window (you can redirect console though). If your program sends something to STDOUT or STDERR, you'll usually get an e-mail. So have a look at /var/spool/mail/myname (or the location where your system locally stores e-mails). For further experiments, I suggest to use a simple cron-command like /bin/date >> /tmp/mycrontabcheck.txt. Each time, your cronjob is executed, it is documented in /tmp/mycrontabcheck.txt

      I would be surprised if your cron-daemon is not running..., however  ps -elf | grep cron | grep root should come up with something like /usr/sbin/cron or ...crond.

      Security: man crontab explains what you have to do regarding the /etc/cron.allow and /etc/cron.deny issues better than I can do here, but shortly: if /etc/cron.allow exists, your UID (myname?) must be a single linefeed terminated line in this file. If this file does not exist, your UID must not be listed in /etc/cron.deny (neither: ALL).

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