Dear wise ones-

I have a script whose purpose is to secure-copy a file to a remote host. I'm using the Net::SCP::Expect module (which ultimately calls Expect.pm itself) to perform the 'scp' command.

This script is intended to be run from cron (and another third-party job management package, Autosys, we use here in shop).

Anyhow, the problem is apparent in both cron and Autosys. When run from the command line, the script runs fine. It secure copies the file from the local host to the remote one correctly. The problem arises when I attempt to run the same script (as the same user) from cron.

Below is the Expect::spawn code.

Expect forks to run the 'scp' command and when run from the command line the following fork call returns a value greater than zero, when run via cron the fork call returns a zero value and execution stops on the subsequent 'close(STDOUT)' call within the Expect.pm::spawn() subroutine.

I noted below where it stops:

sub spawn {
   ...
   ...
   my $pid = fork;

   unless (defined ($pid)) {
      warn "Cannot fork: $!" if $^W;
      return undef;
   }

   if($pid) {
      # parent
      my $errno;
      ${*$self}{exp_Pid} = $pid;
      close STAT_WTR;
      $self->close_slave();
      $self->set_raw() if $self->raw_pty and isatty($self);

      # now wait for child exec (eof due to close-on-exit)   
      # or exec error
      my $errstatus = sysread(STAT_RDR, $errno, 256);
      die "Cannot sync with child: $!" if not defined    
         $errstatus;
      close STAT_RDR;
      if ($errstatus) {
         $! = $errno+0;
         warn "Cannot exec(@cmd): $!\n" if $^W;
         return undef;
      }
   }
   else {
      # child
      close STAT_RDR;
   
      $self->make_slave_controlling_terminal();
      my $slv = $self->slave()
         or die "Cannot get slave: $!";
   
      $slv->set_raw() if $self->raw_pty;
      close($self);

      close(STDIN);
      open(STDIN,"<&". $slv->fileno())
         or die "Couldn't reopen STDIN for reading, $!\n";

      #
      # ---- execution stops/waits on the call below ----
      #
      close(STDOUT);

      open(STDOUT,">&". $slv->fileno())
         or die "Couldn't reopen STDOUT for writing, $!\n";
      close(STDERR);
      open(STDERR,">&". $slv->fileno())
         or die "Couldn't reopen STDERR for writing, $!\n";
   
      { exec(@cmd) };
      print STAT_WTR $!+0;
      die "Cannot exec(@cmd): $!\n";
   }
}
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I have tried numerous alternative methods of execution, ranging from having cron call a 'driver' script that does a system() call to execute this script, to autoflushing STDOUT prior to calling new() for Expect, to scouring the NET::SCP::Expect and Expect dcoumentation to see if I'm missing something. Regardless, execution still hangs on that 'close(STDOUT)' call in spawn. It seems that it's blocking on the close, waiting for someone to relinquish the filehandle, I just don't know who. :)

Any help/hints/ideas would be greatly appreciated.

- Camper