Problem with piped filehandle in perl

Question

I am trying to run bp_genbank2gff3.pl (bioperl package) from another perl script that gets a genbank as its argument.

This does not work (no output files are generated):

   my $command = "bp_genbank2gff3.pl -y -o /tmp $ARGV[0]";

   open( my $command_out, "-|", $command );
   close $command_out;

but this does

   open( my $command_out, "-|", $command );
   sleep 3; # why do I need to sleep?
   close $command_out;

Why?

I thought that close is supposed to block until the command is done:

Closing any piped filehandle causes the parent process to wait for the child to finish... (see http://perldoc.perl.org/functions/open.html).

Edit

I added this as last line:

say "ret=$ret, \$?=$?, \$!=$!";

and in both cases the printout is:

ret=, $?=13, $!=

(which means close failed in both cases, right?)

Answer 1

I'm not sure what you're trying to do but system is probably better in this case...