use strict;
use warnings;

# Open your $rh and authenticate here
# ...

open(my $fh, "+>>default_ve.txt") || die "Couldn't open file: $!";
my @lines = $rh->cmd(String => 'show version | no-more', Prompt => '/\n\S+\>/');
foreach my $line (@lines) {
  print $fh $line;
}
close $fh;

# Close $rh or do more stuff here
# ...