CODEWITHSUNDEEP
perlvariables
Bill
Bill

Reputation: 1247

Can I use the .perl_env file to set env variables?

I am new at configuring perl and I'm trying to find the best way to set some common variables. I know there are lots of ways of doing this but I want to find the "best" ;). I came a crossed the .perl_env file in my root dir but can't find much documentation on it. Is this a place I can keep variables like BINDIR and VARDIR (locations that I use in my perl scripts) or is there a better way. Thanks!!

Upvotes: 0

Views: 252

Answers (4)

Joel Berger
Joel Berger

Reputation: 20280

Like everyone else, I've never heard of a .perl_env file. Also I'm assuming you mean that you want to set Perl global variables, since if you mean to set system global variables (environment variables) you should be doing that in a Bash script.

Anyway, if you really wanted to do this I would make a file named MyGlobalVariables.pm and place it in your PERL5LIB directory.

package MyGlobalVariables;

use strict;
use warnings;

use parent 'Exporter';
our @EXPORT = qw/$SomeVar/;

our $SomeVar = 'Some Value';

Remember that each variable must be added to the @EXPORT array.

Then in your scripts you can write use MyGlobalVariables; and voila, there they are. This mechanism is a lot like a custom style file in LaTeX; of course that is a macro language.

All that said, I really don't think this is a good idea. Why? Two reasons:

  1. You cannot see the initialization of these variables, to remember you have to go look in the other file.
  2. These variables must be true globals rather than lexicals. One always should use lexicals (my rather than our) unless there is a real reason to do so.

Upvotes: 2

Bill Ruppert
Bill Ruppert

Reputation: 9026

For global variable like that, I have them set in the environment (I use Windows, but obviously you can do the same in Unix). In Perl, the environment is stored in the %ENV variable (part of the system.) You would refer to your BINDIR as $ENV{BINDIR}.

Upvotes: 1

Gilles Quénot
Gilles Quénot

Reputation: 185504

If you want to deal with a configuration file to share variables between scripts, see the following example :

INPUT file:

$ cat /tmp/config 
[name1]
    val1=foobar
    val2=qux

[name2]
    val1=10
    val2=100

Perl code :

$ perl -we '
    use Data::Dumper;
    use Config::IniFiles;
    my $ini = new Config::IniFiles(
        -file => "/tmp/config", -allowcontinue => 1
    );
    print Dumper $ini->{"myparms"};
'

OUTPUT :

$VAR1 = {
          'name2' => [
                       'val1',
                       'val2'
                     ],
          'name1' => [
                       'val1',
                       'val2'
                     ]
        };

If instead you need a shell variable to share, by example if using bash :

$ echo "export MYVAR=foobar" >> ~/.bashrc
$ . !$
$ perl -le 'use Env qw/MYVAR/; print $MYVAR;'

Upvotes: 1

ikegami
ikegami

Reputation: 386256

Hum, I've never heard of .perl_env, and it's not in the documentation:

$ perldoc perlrun | grep .perl_env || echo "not found"
not found

But let's give it a try anyway.

$ echo '$ENV{FOO}="BAR";' >~/.perl_env

$ FOO=BAZ perl -E'say $ENV{FOO}'
BAZ

Nope, doesn't work.

Upvotes: 2

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