How do I redirect the output of Perl script executed from within another perl script to a file?

Question

I am running a perl script via crontab and redircting its output to a file:

30 1 * * * /full/path/to/my_script.pl >> /full/path/to/my_log_file

Within my_script.pl, I'm executing several other perl scripts via the system() command:

#/usr/bin/env perl
system( "/full/path/to/another_script.pl" );

And within those scripts, I am using 'print' to write to STDOUT:

#/usr/bin/env perl
print "Standard output...\n";

It appears, however, that none of those child scripts' output is getting redirected to my_log_file- The only output I see there is that of the parent perl script. Am I missing something obvious? This is on a linux system.

Pedro Silva · Accepted Answer · 2011-09-16 01:04:15Z

1

Instead of system(), use qx:

print qx( "/full/path/to/another_script.pl" );

answered Sep 16, 2011 at 1:04

Pedro Silva

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pgregg · Accepted Answer · 2011-09-16 00:34:41Z

0

Hmmm, if using system() then STDOUT should end up back in your log.

Do you have an example?

My immediate thoughts go towards the system() call isn't actually running the other scripts - do you use a full path to the script? Remember cron wont have the same $PATH that your shell has, so may not find the scripts you are trying to run unless they have the full path.

You could also capture STDERR in your log: 30 1 * * * /my_script.pl 2>&1 >> my_log_file

answered Sep 16, 2011 at 0:34

pgregg

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5 Comments

todd412 Over a year ago

That's interesting, would that technique of using "@>&1" capture both STDOUT and STDERR to my_log_file? And yes, I am using full paths to the main script within the crontab and to the sub-scripts from within the system() commands.

todd412 Over a year ago

I added some additional details to my original post.

pgregg Over a year ago

Yes - 2>&1 causes filehandle 2 (STDERR) to be redirected to filehandle 1 (STDOUT). Then the use of >> (for STDOUT) results in both STDOUT and STDERR output going to your logfile.

pgregg Over a year ago

#/usr/bin/env perl <--- is perl in cron's PATH? Tho i expect if it works in the parent, it works in the subscript.

pgregg Over a year ago

Other things to check: The return value of system() - it should be 0. Try using backticks $output = ``/full/path/to/another_script.pl``; print $output; (ok - I can't work out how to make this show a single backtick since that is the markup for "code") and trap errors. eval { system(" .. "); }; if ($@) { print "ERROR: $@\n"; }

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