using perl for a cron job

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I realize this is more of a techical question but I know someone here has used perl for a cronjob on their web server before.

I have a script that doesn't collect any data, it just loads pages. All it does is print a few things to the screen (which would be discarded when it's in CGI format as I won't care about any of the output).

Question is, is it possible to run a perl script that doesn't take much memory for days on end? Or like CGI files, would there be a timeout if the script doesn't complete in enough time?

I just want to keep a script running on my web host for a few days, think it's possible?

Comment on using perl for a cron job

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Re: using perl for a cron job by Zaxo (Archbishop) on May 24, 2006 at 18:29 UTC
Do you want to run it continually, or periodically? For the latter, `cron` is what you want. See `man crontab` for how to set it up. You can give the crontab more or less the same command line you would use in a terminal session. For continuous running, your script needs to be written to do that. One way is with Proc::Daemon, and an endless loop. After Compline, Zaxo	[reply]
Re^2: using perl for a cron job by Anonymous Monk on May 24, 2006 at 22:58 UTC
I'd like to run the script once a day and self-kill it if it's possible. It just loads pages and pages and pages nonstop and it literally takes about 3 days to finish, but I'd restart it once a day. It doesn't use any files outside of the perl script itself, it's a simple little script using a while loop that takes about 3 days to finish.	[reply]
Re: using perl for a cron job by samtregar (Abbot) on May 24, 2006 at 18:27 UTC
Simple answer: yes - long running Perl processes are definitely possible. Long answer: yes, but consider what might happen if your long running process is started while a previous run is still happening. You can avoid this using lockfiles or pid-files, for example. You might also find Proc::Daemon useful to get your program running without a terminal (although if you use cron to launch it you won't have to do this). For an example of a long-running Perl daemon you could look at Krang's scheduler and FTP daemons. -sam	[reply]
Re: using perl for a cron job by GrandFather (Saint) on May 24, 2006 at 18:26 UTC
Yes. DWIM is Perl's answer to Gödel	[reply]
Re: using perl for a cron job by izut (Chaplain) on May 24, 2006 at 18:36 UTC
cron allows you execute long running jobs, but it's safer that you handle the timeouts of your application by doing something like that: `$SIG{ALRM} = sub { die "Game over!"; } alarm(10); sleep(20);` [download] More info on perlipc. Igor 'izut' Sutton your code, your rules.	[reply] [d/l]