Using "at" to run a perl script (does'nt seem to work?)

[Joel Shank]

I am trying to submit a perl script via an at command, but I am getting shell errors (mostly things like: sh[30]: =: not found.

The script works fine if I just run it via ./pgm, but not when I run it as:
at -f /home/root/pgm now

I am using HP_UX 11.00 and perl v5.6.0

Does anyone know if I can run a perl script via the at command? I know it works via cron as I have scheduled several perl scripts using crontab.

Any assistance would be greatly appreciated.
jls

[RAC_1]

Yes you can run any script with at.

Make sure you have #!/opt/perl/bin/perl or what ever is the perl path at the start of the script.
Also make sure all required variables are defined and exported in script file.

Anil

[Pete Randall]

Joel,

Make sure you use the full path names of any commands in your script.


Pete

[A. Clay Stephenson]

Yes you can but you have to play by a few rules. Make sure that you have a "shebang" as the very first line of your Perl script.

#!/usr/bin/perl -w


Almost all problems stem from the intentionally very sparse environment under which cron spawns new processes. You may also need to add -I arguments to tell Perl where to look for modules.

Probably the easist way to to let cron invoke a shell script which in turn sets and exports any needed enviroment variables like PATH and then let this shell script actually launch the Perl script.

[H.Merijn Brand (procura · Accepted solution]

If I'm not mistaken, all of the above answers are wrong.

both at and cron only take SHELL scripts, and disregard the header line, which is pretty counterintuative

Look at this:
--8<---
a5:/u/usr/merijn 111 > tty
/dev/ttyp2
a5:/u/usr/merijn 112 > cat xx.pl
#!/pro/bin/perl

use strict;
use warnings;

open STDOUT "> /dev/ttyp2";
print "Hello, world\n";
a5:/u/usr/merijn 113 > at -f xx.pl now
warning: commands will be executed using /usr/bin/sh
job 1084814691.a at Mon May 17 19:24:51 2004
a5:/u/usr/merijn 114 >
-->8---

look at the warning at gives!

The difference with cron is that you enter the executable perl script as a name in the cron line. The cron line is evaluated by /usr/bin/sh, and thusly nicely interprets the shebang line

Enjoy, Have FUN! H.Merijn [ leaving extending this knowledge to call perl in at to the user ]

[H.Merijn Brand (procura]

And I forgot to add the mail I got:

--8<---
sh[55]: use: not found.
sh[56]: use: not found.
sh[58]: open: not found.
Hello, world



*************************************************
Cron: The previous message is the standard output
and standard error of one of your at commands.


-->8---

It prooves I'm right :)

Enjoy, Have FUN! H.Merijn

[Joel Shank]

I know to use the shebang. It seems procura is correct, the at command ignores the header and runs it via the shell regardless as to the header setting.

I found that if I write a shell script that calls the perl script it works without error.

This is a pain, since the shell SHOULD interpret the shebang!

At any rate, I can get it to work properly even it is an ugly way to do it.

Thanks to all for quick responses.

jls

[Fred Ruffet]

Ooops :)

/tmp#cat test.pl
#!/opt/perl/bin/perl

$var=2;
$var+=2;
printf "$var\n";
/tmp#crontab -l
44 19 * * * /tmp/test.pl > /tmp/test.log 2>&1
/tmp#cat test.log
4

Seems that it works for me...

Regards,

Fred

[Fred Ruffet]

re-Ooops ;)

Didn't saw the at/crontab problem. works with cron, don't with at.
You're absolutly right procura

Regards,

Fred