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perldebuggingtrace

Is there a way to turn on tracing in perl (equivalent to bash -x)?

I have a system script in perl. I need some equivalent of bash -x to determine what is going wrong with the script. Is there something equivalent?

EDIT: What bash -x does is that it prints each line as it is evaluated. This makes debugging code that is just missing some path variable or file very easy.

Solution

  • Take a look at Devel::Trace or Devel::ebug.

    Given this program named w.pl:

    #!/usr/bin/perl

use strict;
use warnings;

my $answer = 42;

if ($answer == 6 * 9) {
    print "everything is running fine.\n";
} else {
    warn "there must be a bug somewhere...\n";
}

    You can use Devel::Trace to watch the execution:

    perl -d:Trace w.pl

    Which produces the following output:

    >> w.pl:6: my $answer = 42;
>> w.pl:8: if ($answer == 6 * 9) {
>> w.pl:11:     warn "there must be a bug somewhere...\n";
there must be a bug somewhere...