use strict;
use warnings;
use Data::Dumper;

my ( $ipaddress, $prefix, $interface, $device, $location) = ('no_ws', ' some_ws ', undef, '  lotsa  ws  ', undef);
s/^\s+|\s+$//g for grep {defined $_} ( $ipaddress, $prefix, $interface, $device, $location);

print Dumper ( $ipaddress, $prefix, $interface, $device, $location);