Hi, i wanted to use ipc::open3 to control a process, here is the code of wrapper.pl 
use strict;
use IPC::Open3;
use IO::Select;
use Carp;

my $cmd = "ls -al";
my $pid = open3( *cmdIn, *cmdOut, *cmdErr, $cmd) or die "can not open 
+$cmd $!";
print "\$pid $pid"; print "\n";
$SIG{CHLD} = sub {

  print "result: Status $? in $pid\n" if waitpid($pid, 0) >0
    
};

my $select = IO::Select->new(*cmdErr, *cmdOut);
print cmdIn "\n\n$cmd\n";
close(cmdIn); 
my $input; 
while ( my @ready = $select->can_read()) { 
    foreach my $fh ( @ready ) { 
    if (fileno($fh) == fileno(cmdErr)) { 
              process_errors(); 
    
    } else { 
            print "STDOUT: ", <$fh>;
        }
    $select->remove($fh) if eof($fh);
    } 

} #
close (cmdOut);
close(cmdErr);

sub process_errors { 
    my $select= IO::Select->new( *cmdErr ); 
    my $input; 
        while ( $select->can_read(0.1) ) { 
        sysread *cmdErr, (my $line), 1024; 
    
    last unless $line; 

    $input.= $line;
    
    } 
        croak "THERE: $input $cmd code" if $input =~ /error:/; 
        carp "HERE: $input $cmd code" if $input;
    

} 

{ 

    local $SIG {__WARN__} = 

    sub { 

    my $warning = shift ; # warning handler 

    }; # commands 

}

[download]
When i run the wrapper.pl, often it does $cmd (ls -al), listing the files in the shell, but sometimes not, no output! WHY? 
/home/murcia # ./wrapper.pl
$pid 11685                      <<<<< OK 
STDOUT: total 48
-rwxr-xr-x    1 murcia     users           77 Dec 14 11:30 test.pl
result: Status 0 in 11685
/home/murcia # ./wrapper.pl
$pid 11687                             <<<< not OK
/home/murcia #

[download]
When I use a cmd which needs a short time, it seems to fail more often??? for a long cmd not??? Best regards Murcia

In reply to ipc::open3 start process by Murcia

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