my $txt = <$fh> This reads the first line from $fh and assigns it to scoped (my) variable named $txt. there is nothing wrong with that (it is *not* a copy). The rest of it however, is suspect. Something like this might be better

use Symbol;
...
 socket($SOCK=gensym(), PF_INET, SOCK_DGRAM, $proto);
...
Otherpackage::foo($SOCK) 
...
package Otherpackage;
sub foo { my $fh = shift; }
[download]

--
perl -p -e "s/(?:\w);([st])/'\$1/mg"