Twig in a crontab?

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

I have this little program:

lauxastst01:~/bin:cat test.pl
#!/usr/bin/perl -w
use strict;
use Date::Manip qw(UnixDate);
use XML::Twig;

print "OK!\n";
[download]

When I run it from the command line, it outputs OK! When I run it as a cron job, it outputs this:

Can't load '/usr/local/perl/5.8.2/lib/site_perl/5.8.2/sun4-solaris/aut
+o/XML/Parser/Expat/Expat.so' for module XML::Parser::Expat: ld.so.1: 
+perl: fatal: libexpat.so.0
: open failed: No such file or directory at /usr/local/perl/5.8.2/lib/
+5.8.2/sun4-solaris/DynaLoader.pm line 229.
 at /usr/local/perl/5.8.2/lib/site_perl/5.8.2/sun4-solaris/XML/Parser.
+pm line 14
Compilation failed in require at /usr/local/perl/5.8.2/lib/site_perl/5
+.8.2/sun4-solaris/XML/Parser.pm line 14.
BEGIN failed--compilation aborted at /usr/local/perl/5.8.2/lib/site_pe
+rl/5.8.2/sun4-solaris/XML/Parser.pm line 18.
Compilation failed in require at /usr/local/perl/5.8.2/lib/site_perl/5
+.8.2/XML/Twig.pm line 98.
BEGIN failed--compilation aborted at /usr/local/perl/5.8.2/lib/site_pe
+rl/5.8.2/XML/Twig.pm line 98.
Compilation failed in require at ./test.pl line 4.
BEGIN failed--compilation aborted at ./test.pl line 4.
[download]

It complains about Expat.so, which, I guess is required by Parser.pm, which, I guess is required by XML::Twig. Notice that I included a 'use' for Date::Manip before XML::Twig to show that it is not incapable of finding all modules, just that it can't find XML::Twig in the crontab environment. What gives?

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Re: Twig in a crontab? by Fletch (Bishop) on Jan 31, 2008 at 04:48 UTC
Not that it's strictly speaking a perl problem, but processes run from cron don't run with the same environment as your normal login shell sets up. Look in your `.profile` / `.bashrc` / whatnot for environment variables such as `LD_LIBRARY_PATH` and what not and either add those to your cron command line, write a shell wrapper which sets them then runs your perl, or set them in a `BEGIN` block in your code (e.g. `BEGIN { $ENV{LD_LIBRARY_PATH} = q{...}; }`). Failing that, find your local sysadmin and they'll probably be able to tell you what needs to be set. The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]
Re^2: Twig in a crontab? by BenHopkins (Sexton) on Jan 31, 2008 at 05:56 UTC
You're probably right. I have LD_LIBRARY_PATH set to (among other things) /usr/sfw/lib, where libexpat.so lives. The bad news is that I've tried both a BEGIN block and setting in the crontab, but neither works. I even did this in the crontab file: `45 21 * * * LD_LIBRARY_PATH=/usr/sfw/lib ; echo $LD_LIBRARY_PATH; cd b +in; ./test.pl` [download] and got this: `Your "cron" job on lauxastst01 LD_LIBRARY_PATH=/usr/sfw/lib ; echo $LD_LIBRARY_PATH; cd bin; ./test.p +l produced the following output: /usr/sfw/lib Can't load '/usr/local/perl/5.8.2/lib/site_perl/5.8.2/sun4-solaris/aut +o/XML/Parser/Expat/Expat.so' for module XML::Parser::Expat: ld.so.1: +perl: fatal: libexpat.so.0 : open failed: No such file or directory at /usr/local/perl/5.8.2/lib/ +5.8.2/sun4-solaris/DynaLoader.pm line 229.` [download] Sigh ... I'll keep trying stuff until it works.	[reply] [d/l] [select]
Re^3: Twig in a crontab? by sids (Acolyte) on Jan 31, 2008 at 06:22 UTC
You can set environment variables at the beginning of the crontab file; cron will automatically export these to your script's environment. Like so: `LD_LIBRARY_PATH=/usr/sfw/lib` [download] If you want to improve, be content to be thought foolish and stupid. -- Epictetus	[reply] [d/l]
Re^4: Twig in a crontab? by BenHopkins (Sexton) on Jan 31, 2008 at 06:47 UTC
Re^5: Twig in a crontab? by MidLifeXis (Monsignor) on Jan 31, 2008 at 18:03 UTC
Re^3: Twig in a crontab? by BenHopkins (Sexton) on Jan 31, 2008 at 07:31 UTC
Just FYI, this is what made it work. I ran a shell script from the cron. It looks like this: `#!/bin/sh LD_LIBRARY_PATH=/usr/sfw/lib export LD_LIBRARY_PATH chdir $HOME/bin ./test.pl` [download] Maybe if I put the export command in the crontab line it would have worked, but it gets real messy when you jam too much stuff in the crontab file.	[reply] [d/l]
Re^4: Twig in a crontab? by Fletch (Bishop) on Jan 31, 2008 at 13:52 UTC
Re: Twig in a crontab? by hipowls (Curate) on Jan 31, 2008 at 07:18 UTC
One answer is to use crle which has a similar function to ldconfig on linux `# show current config crle # create new config crle -l /usr/lib:/usr/local/lib:/opt/swf/lib crle -u` [download] will create a configuration file for the linker so that it knows where to look for dynamic libraries. Warning Read the man page before running any commands.	[reply] [d/l]
Re^2: Twig in a crontab? by Tanktalus (Canon) on Jan 31, 2008 at 23:11 UTC
Of course, the next closest thing is to just create symlinks in /usr/lib to the expat library ;-) (I know new symlinks are needed each time you upgrade the expat library. I know that this will happen so infrequently that you'll need to reinvestigate each time it happens because you won't remember. Shhhh!)	[reply]
Re: Twig in a crontab? by TOD (Friar) on Jan 31, 2008 at 04:37 UTC
does cron run the job as root? if it doesn't check the file permissions on Expat.so -------------------------------- masses are the opiate for religion.	[reply]