Importing environment variables to Perl

问题:

I'm not sure if importing is the right word to use. I'm a beginner in both Perl and Bash. I have set a variable on Bash, so when I do:

echo $PRDIR

it prints a string (It's a directory name)

I want to import that string to Perl, and I don't know how to do that. I've tried:

$varex = system("$PRDIR");
print "$varex";

And also

$varex = system("echo $PRDIR");
print "$varex";

but that doesn't work (I understand the last one, It prints "0" because that's echo's return value). I've also tried redirecting stdout to a variable but I couldn't.

回答1:

If you want Bash to export a variable into the environment so it's accessible to programs, you can use the export builtin:

export PRDIR

Inside Perl, you would then access it using the %ENV hash:

my $varex = $ENV{"PRDIR"};
print "\$varex is: $varex\n";

回答2:

Another solution to use the variable directly in perl :

In the shell :

$ export PRDIR=foobar

In perl :

#!/usr/bin/perl

use Modern::Perl;

use Env qw/PRDIR/;

say $PRDIR;

回答3:

I guess you need something like this:

use Cwd 'abs_path';
use File::Basename;
my $self = abs_path($0);
my $bindir = dirname( abs_path($0) );
unless ($ENV{APP_ENV}) {
    warn "No APP_ENV, will try to get from bin/env.sh";
    exec("source $bindir/env.sh && /usr/bin/perl $self") || die "$!";
}

I have env.sh in my bin folder with following content:

export APP_ENV=development

The idea behind this approach is that I don't need to bother if I set my ENV variables before running my Perl code or forget to do it. I need just to run my Perl program and it will take care about preparing environment for itself.