All,

I'm trying to write a script that will execute a process in the background, monitoring STDOUT and STDERR to obtain data, then print "QUIT" on STDIN to kill off the application. I'm developing on XP but this will run on *nix.

I'm attempting to use open3 and IO::Select to read both STDOUT and STDERR without blocking. It ain't working...

  • if I dumpValue the select handle I never see STDERR get set.
  • I never got into the while because "$sel->can_read" appears to never return a ready handle

    • I'm open to other approaches here. 

    my ($read, $write, $error); 
my $pid = open3( $write, $read, $error, "$em_command &") || die ERROR.
+" : Unable to execute ";

write_log (DEBUG, "Maintenance Proxy pid = $pid");

# exception occured
if ($pid =~ /^open3:/) {
    write_log (ERROR, $pid);  
    exit 1; 
}

my $sel = IO::Select->new();
$sel->add($read);
dumpValue ($sel);
print "---\n";
$sel->add($error);
dumpValue ($sel);
print "---\n";

my ($rh, $inStr);
while(my @ready = $sel->can_read)
{

    foreach my $handle (@ready) {
        
         if ($handle == $error)
         {
            my $numBytesRead = sysread($rh,  $inStr, 1024);
            print "ERROR: $inStr";
         }
         else
         {
            my $numBytesRead = sysread($rh,  $inStr, 1024);
            print "INFO: $inStr";
         }
         $sel->remove($handle) if eof($handle);

     }
 }

    [download]

    In reply to open3 and IO::Select by stephens2k

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