I usually do perldoc -l Data::Dumper at the command line. Just tried it on one of my systems, and I got 

/usr/lib/x86_64-linux-gnu/perl/5.26/Data/Dumper.pm

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in response. To find out the version, I grep for version in that file .. 
$ grep -i '^version' /usr/lib/x86_64-linux-gnu/perl/5.26/Data/Dumper.p
+m
Version 2.167  (January 4 2017)
$

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Conversely, if the perldoc approach doesn't turn anything up, either the module isn't installed -- or it doesn't have POD. Then you could try using it in the debugger: 
$ perl -MData::Dumper -de 1

Loading DB routines from perl5db.pl version 1.51
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:1):   1
  DB<1>

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If that loads OK, then the module does exist. If Perl can't find the module, it'll complain.

Alex / talexb / Toronto

Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.

In reply to Re^3: Roger the Phone Guy by talexb
in thread Roger the Phone Guy by ptx

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