How to access shell environment variables in Perl script

Question: I would like to access several environment variables in my Perl script. How can I access shell variables from a Perl program?

In some cases you may want to access shell environment variables (e.g., $PATH, $PWD, $HOME, $LANG) in your Perl script. While you can pass any needed environment variables to your Perl script via @ARGV argument array, this is actually not needed since Perl provides a way to access all available environment variables. Let's find out how to access shell environment variables in a Perl script.

In Perl, all environment variables are maintained in a special hash named %ENV. To access a particular shell variable abc in Perl, you can simply fetch a hash value for key 'abc'. For example, to access $PATH and $PWD variables in Perl:

my $path_var = $ENV{PATH};
my $pwd_var = $ENV{PWD};
print "PATH: $path_var\n";
print "PWD: $pwd_var\n";

Alternatively, you can use the Perl module called Env, which allows you to access shell environment variables using global Perl variables with the same names. For example, the above example code can be rewritten by importing Env module as follows.

use Env;

print "PATH: $PATH\n";
print "PWD: $PWD\n";

The Env module also allows you to import an environment variable as an array. For example:

use Env qw(@PATH);

foreach (@PATH) {
  print "$_\n";
}

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