in reply to Re^2: Perl Background processes in Windows
in thread Perl Background processes in Windows

@ Peter Dragon, Did you ever test your script? It can never work as the script starts with a die........

A conditional die, makes all the difference in the world 

$ perl -le " die 6 if 9 "
6 at -e line 1.

$ perl -le " die 6 if not 9 ; die 8 "
8 at -e line 1.

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Re^4: Perl Background processes in Windows
by gepebril69 (Scribe) on Jan 31, 2012 at 10:22 UTC
    @Peter Dragon, You are right. Maybe I posted to quickly, but no matter what $cmd I use (dir|date|xxxx.exe) it will always fail on my Windows7 x64 machine. It looks very strange to me that you can use a system call in that way. Normally you use something like `$cmd` or system() to execute a system call.
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      Consider looking at perlop to see what -x does. Also, if it "always fails" (and you're interested in learning why), consider posting full code.

      Please note that dir and date are shell builtins in cmd.exe and thus never pass -x, because they are not programs that can be run. Also note that -x expects the full path to an executable and does not search $ENV{PATH}. Whether that is desired or not in the context of the above program, I don't know. Update: As the argument is passed to Win32::Process::Create(...), it makes sense to have a fully specified path, because that's what Win32::Process::Create() likely wants.

      >perl -wle "print $_, -x $_ ? ' yes':' no' for @ARGV" cmd.exe c:\WINDO
+WS\system32\cmd.exe
cmd.exe no
c:\WINDOWS\system32\cmd.exe yes

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      As to using system or backticks, these do not launch a background process. Which seems to be the purpose of the code under discussion. Actually, perlport points out system(1, ...) for launching a process in the background under Windows and OS/2.

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        Proc::Background - Generic interface to Unix and Win32 background 

                use Proc::Background;
        timeout_system($seconds, $command, $arg1);
        timeout_system($seconds, "$command $arg1");

        my $proc1 = Proc::Background->new($command, $arg1, $arg2);
        my $proc2 = Proc::Background->new("$command $arg1 1>&2");
        $proc1->alive;
        $proc1->die;
        $proc1->wait;
        my $time1 = $proc1->start_time;
        my $time2 = $proc1->end_time;

        # Add an option to kill the process with die when the variable
+ is
        # DETROYed.
        my $opts  = {'die_upon_destroy' => 1};
        my $proc3 = Proc::Background->new($opts, $command, $arg1, $arg
+2);
        $proc3    = undef;

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