use strict;
use warnings;

package MyPkg;

sub my_name_is {
   ${$_[0]} = $_[1];
}

1;

package main;
my $name_aus_main = "Du";

print "1) my_name: $name_aus_main\n";
MyPkg::my_name_is(\$name_aus_main, 'Ich');
print "2) my_name: $name_aus_main\n";