Why can't my Perl script load a module when run by cron? - perl

Question

I have a bunch of Perl scripts that all run fine, yet need to have use Plibdata; up top.
I set up a cron job that runs (I get the confirmation email from root) and it spits back the following error message:
Can't locate Plibdata.pm in #INC (#INC contains: /install/lib /opt/perl58/lib/5.8.8/IA64.ARCHREV_0-thread-multi /opt/perl58/lib/5.8.8 /opt/perl58/lib/site_perl/5.8.8/IA64.ARCHREV_0-thread-multi /opt/perl58/lib/site_perl/5.8.8 /opt/perl58/lib/site_perl .) at ./x line 5.
BEGIN failed--compilation aborted at ./x line 5.
Line 5 is... you guessed it.... use Plibdata;
I am also attempting to set the environment as such:
use lib "$ENV{CARSPATH}/install/lib";
so maybe if I found the location of this plibdata, I could explicitly direct it that way?
My cron commands will be executed using /usr/bin/sh says crontabs...
Any suggestions?
This script works from the command line.

Answer 1

You don't say what Plibdata is. You also don't state if this works at your command prompt. I assume that it does.
Try this:
perl -MPlibdata -e 1
Assuming that doesn't spit the same error, try this:
perl -MPlibdata -le 'print $INC{"Plibdata.pm"}'
That will tell you where. (It's probably in your PERL5LIB env var if this works.) Then you can just add the appropriate "use lib" to the directory Plibdata.pm is in.
Also, be sure you're using the same perl in both locations - command line ("which perl") and in the cron job (try "BEGIN { print $^X }" at the top of your script).

Answer 2

Cron uses a different user env than your env when logged in. Are you able to run the script from the command line? If so, just set your env variables inside the cron above your current commands.

Answer 3

Clearly, Plibdata.pm is not installed in the default module paths on your system:
/install/lib /opt/perl58/lib/5.8.8/IA64.ARCHREV_0-thread-multi /opt/perl58/lib/5.8.8 /opt/perl58/lib/site_perl/5.8.8/IA64.ARCHREV_0-thread-multi /opt/perl58/lib/site_perl/5.8.8 /opt/perl58/lib/site_perl
You have three choices:
Install Plibdata.pm in a known Perl system path (site_perl is the classic option).
Make the PERL5LIB shell environment (or the equivalent command line -I option for Perl) include the installation path of the module.
Use use lib in your script. Remember that the use lib action is done at compile time, so your variable in the path may not be initialised. Try using the variable in a BEGIN block like this:
my $env;
BEGIN {
$env = $ENV{CARSPATH};
}
use lib "$env/install/lib";

Answer 4

Running your program from a wrapper script as others have suggested is probably my preferred method, but there may be a few other solutions:
If you're using a modern cron you may be able to do something like this in your crontab entry:
* * * * * CARSPATH=/opt/carsi x
replacing the asterisks with the appropriate schedule designators.
This will set CARSPATH for the x process and allow the use lib statement that passes the environment variable to work.
You can also, depending on your shell and cron implementation, store your environment setup in a file and do something like:
* * * * * source specialenv.sh && x
Where specialenv.sh contains lines like (for bash)
export CARSPATH=/opt/carsi
You may also be able to set environment variables directly in the crontab, should you choose to do so.

Answer 5

cron does not setup an environment for you when it runs your code, so the environment variable $CARSPATH does not exist. I suggest only running shell scripts from cron, setting the environment inside of the shell script and then running the program you really wanted to run.
example wrapper script:
#!/bin/bash
source ~username/.bash_profile
cd ~username
./script.pl
If you are using ksh or sh you may need to say
#!/bin/sh
. ~username/.profile
cd ~username
./script.pl
Remember to replace username with your username on the system. Also, if the script is not in your home directory you will want to execute it with the path to it, not ./.
You say source, or period space, to load a given shell script in the current shell. You load it in the current shell so that any environment settings stay with the current shell.
~/.bash_profile, ~/.bashrc, ~/.profile, /etc/profile, etc. are all files that commonly hold your environment setup. Which one you are using depends heavily on your OS and who set it up.

Answer 6

Although its not an 'answer', I resolved this issue by using DBI instead of the Plibdata.
Which is kind of milky because now I will have to change a couple scripts around... ahhhhh I wish there was something I could do to make the Plibdata work
I'm still going to try Chas. Owens answer to see if that works
didn't work for me... "interpreter "/bin/bash" not found"maybe it would work with people who have that interpreter
* * * * * CARSPATH=/opt/carsi ./x
works