Hi, Try this one

use strict;
use warnings;

my ($a, $b, $c) = @ARGV;

open(FILE, "$a");
my $text=do {local $/; <FILE>};
close FILE;

my %mymatch = $text =~ m/^\s*(.*?)\s*\=\s*(.*?)\s*$/igm;

open(FILE, "$b");
my $maintext=do {local $/; <FILE>};
close FILE;

foreach my $myfnd (sort {length($b) <=> length($a)} keys %mymatch) {
    $maintext =~ s/\Q$myfnd\E/$mymatch{$myfnd}/ig;
}

open(FILE,">$c");
print FILE $maintext;
close FILE;
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