G'day perlUser345,

Welcome to the Monastery.

Here's one way to do it:

#!/usr/bin/env perl -l

use strict;
use warnings;
no warnings 'uninitialized';

my @out_records;
my $re = qr{ ^ ( .* ) \s ( \d+ ) $ }x;

/$re/ and $out_records[$2 - 1] = $1 while <DATA>;
print for @out_records;

__DATA__
Line 5 5
Line 1 1
Line 3 3
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Output:

$ pm_1131675_order_out_by_input_spec.pl
Line 1

Line 3

Line 5
[download]