my $oldfh = select(FH);
    $| = 1;
    select($oldfh);
[download]

    FH->autoflush(1);
[download]

The second method requires IO::Handle to be loaded (directly or otherwise).

I have found that if the script is interupted or closed via task manager then much of the log file is lost.

Observe the following code:

use IO::Handle;
use strict;

$|=1;

my $io=new IO::Handle;
open LOG,">> mylofile.txt" or die "mylogfile.txt: $!";

$io->fdopen(fileno(LOG),"w+") or die $!;

$io->autoflush(1);

my $foo=0;
while(1){

        $foo++;
        printf "Iteration: %d\n",$foo;
        $io->printf("Looped in %d\n",$foo);
        sleep 2;
}
[download]

I normally don't do Windows, but since I had a VMWare session going I fired up a quick test of your problem. Ran the above code and killed it with the Task Manager and no data was harmed in the making of rhis node. (Everything I expected was in the log file!)

That's needlessly complicated. LOG and $io? autoflush and other IO::Handle methods can be used on any file handle, including barewords. That means that only LOG is needed. Or better yet, a lexical var ($log).

use strict;
use warnings;

use IO::Handle;

my $log_file = 'mylogfile.txt';

open my $log, '>>', $log_file
   or die "Unable to open log file \"$log_file\": $!\n";

STDOUT->autoflush(1);
$log->autoflush(1);

my $foo=0;
while(1){
   $foo++;
   printf "Iteration: %d\n",$foo;
   $log->printf("Looped in %d\n",$foo);  # or printf $log ...
   sleep 2;
}
[download]

I also

• improved the error message,
• used the safer 3-arg open,
• made the log file name easily editable, and
• avoided the cryptic $|.

$log->autoflush(1);
[download]

Actually, I tried just that prior to my post. It errored out on me. Possibly the version of Perl that was installed on my VMWare virtual machine is at fault. At any rate if it works for you, use it. If not, my solution is just as valid.

Not sure I understand your comment about $| being cryptic. Seems like Perl 101 to me...

---

Peter L. Berghold -- Unix Professional
Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg

I believe Task Manager just sends a SIGTERM.

There's no such thing as signals in Windows. The closest parallel is the message queues of windows.

Furthermore, Task Manager's behaviour varies depending on which tab ("Applications" or "Processes") the item being terminated is located.

When "ending" a "Process", the application is forcibly terminated. ( Reference: TerminateProcess(hProcess, uExitCode) )

When "ending" an "Application", it sends a WM_QUIT WM_CLOSE message to the window. If the application is still running after a small period of time, the user is told the process is not responding, and he is asked whether he wants to terminate the process or not. If the user chooses to terminate the process, it is forcibly terminated. ( Reference: EndTask(hWnd, FALSE, TRUE) )

Is Perl capable of handling Windows messaging? I know that if you were writing a Windows app, you could just have a message loop and handle the WM_CLOSE message.

Windows does not use UNIX signals.

This is a piece of Windows software that sends various kinds of close commands to windows programs. It can send specifics including WM_CLOSE and SC_CLOSE. I believe that TaskManager uses User32.dll->EndTask().

Check this out, it can kill anything:

Advanced Process Termination