use Fcntl ':flock'; # import LOCK_* constants
sub gencli {
  open my $fh, '<', $gencli or die "Can't open $gencli $!";
  flock ($fh, LOCK_EX) or die "Can't lock $gencli  for reading: $!";
  wantarray ? <$fh> : [<$fh>];
}

my $gencli_ref = gencli(); # both of these
my @gencli_ary = gencli(); # work