CODEWITHSUNDEEP
perlenvironment-variables
user7305
user7305

Reputation: 6011

How do I set an environment variable in Perl?

How do I set an environment variable in Perl?

I want to set HOME to a different directory than the default.

Upvotes: 21

Views: 45614

Answers (5)

Mak_Thareja
Mak_Thareja

Reputation: 177

When the Perl executable gets started, it makes it own subshell. That sub shell does not contain all features, like sourcing a shell file which are available only for main shells. You can not set any environment path for your main shell.

You can do one thing if you have a shell file from where you want to access your paths you can use it in your code.

You can do this by installing external module from CPAN which is Shell::Source.

$env_path = Shell::Source->new(shell => "tcsh", file => "../path/to/file/temp.csh");
$env_path->inherit;
print "Your env path: $ENV{HOME}";

As Perl creates its own instance while running on a shell, we can not set an environment path for the main shell as Perl's instance will be like subshell of the main shell. Child process can not set environment paths for parents.

Now till Perl's sub shell will run, you'll be able to access all the paths present in your temp.csh file.

Upvotes: 1

Randall
Randall

Reputation: 3044

If you need to set an environment variable to be seen by another Perl module that you're importing, then you need to do so in a BEGIN block.

For example, if useing DBI (or another module that depends on it, like Mojo::Pg), and you want to set the DBI_TRACE environment variable in your script:

use DBI;
BEGIN {
   $ENV{DBI_TRACE}='SQL';
}

Without putting it in a BEGIN block, your script will see the environment variable, but DBI will have already been imported before you set the environment variable.

Upvotes: 2

innaM
innaM

Reputation: 47889

You can do it like this:

$ENV{HOME} = 'something different';

But please note that this will only have an effect within the rest of your script. When your script exits, the calling shell will not see any changes.

As perldoc -v %ENV says:

%ENV The hash %ENV contains your current environment. Setting a value in "ENV" changes the environment for any child processes you subsequently "fork()" off.

Upvotes: 41

Cosmic Dust
Cosmic Dust

Reputation: 5

It's cheesy, but you could call a VBS script using system("cscript your_vbs_script") to have it handle the environment variable assignment. It will exist for the next shell opened, not the running shell in that case.

Upvotes: -4

David
David

Reputation: 802

$ENV{'HOME'} = '/path/to/new/home';

Also see perlrun

Upvotes: 8

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