use strict;
use warnings;

our $test = {
    first => {
        one => { number => 1 },
        two => { number => 2 },
        three => { number => 3 }
    },  
    second => {
        one => { number => 1 }, 
        two => { number => 2 }, 
        three => { number => 3 }
    },  
    third => {
        one => { number => 1 }, 
        two => { number => 2 }, 
        three => { number => 3 }
    }   
};  

my $input = <STDIN>;
$input =~ s/\n$//;

my $dump = $test->{$input};

use Data::Dumper;
print Dumper( $dump ), "\n";


__END__

% myprog.pl
first
$VAR1 = {
          'three' => {
                       'number' => 3
                     },
          'one' => {
                     'number' => 1
                   },
          'two' => {
                     'number' => 2
                   }
        };
[download]

see also:

• chomp instead of s/\n$//
• perldsc

That worked too but I was looking for something that would dump $a->{$b}->{$c}... rather than just $a->{$b}.

Thanks for your answer!

I would use something like Data::Diver to get the reference.

As an alternative approach, if you're willing to use Perl syntax, you could get the reference using eval, with the problem that you can also call functions etc. from eval:

my $dump= eval $input;
if( my $err= $@ ) {
    warn $err;
} else {
    print Dumper $dump;
};
[download]

This worked perfectly.

Thanks!

One alternate (using Dumper omitted, because how to do so is not the root of OP's problem):

>perl -E "while (<STDIN>) {say shift; push @input, $_;} say @input;"
foo bar baz

bat

sit

sat

sot

^Z
foo bar baz
bat
sit
sat
sot
[download]

Another way, with slight (and adaptable) variation on OP's spec:

C:>perl -E "use Data::Dumper; say Dumper @ARGV;" foo bar baz bat
$VAR1 = 'foo';
$VAR2 = 'bar';
$VAR3 = 'baz';
$VAR4 = 'bat';
[download]

Nevermind - misread the question!

Interpolation is messing up your input. Print out the value of your variable to see what it is. Also, I would use shift instead of STDIN to get the values included on the command line.

$input = shift;
print "$input\n";
[download]