push(@fallend,$_[-1])

push(@fallend,$line)

Use of uninitialized value in concatenation (.) or string at ../cut.pl line 78, <$fh> line 137467.
Use of uninitialized value in concatenation (.) or string at ../cut.pl line 78, <$fh> line 139459.
Use of uninitialized value in concatenation (.) or string at ../cut.pl line 78, <$fh> line 145435.

$set .= ( $last . "\n" ) x 9;

 my $last = ( split /\n/, $set )[-1];
 $last = "" unless($last);
 $set .= ( $last . "\n" ) x 9;
 $set .= $_ . "\n" for (@fallend);
 $set .= "\n\n";
 return $set;

#!/usr/bin/perl

use strict;
use warnings;

my $string; # keine Initialisierung

print $string;

my $string_2 = "hallo"; # mit Initialisierung

print $string_2;