#!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = new MainWindow;
$mw->title("Close test");
$mw->geometry("400x250");

#prevents mw from closing
$mw->protocol('WM_DELETE_WINDOW' => sub {
                print "do stuff here before the exit\n";
        exit;
           });

MainLoop;
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Thank you Zentara. Appreciate it.

Sorry for a little extension to this question, what is the signal name/code when we kill process using CTRL+ALT+DEL task manager Can we catch it and take cleanup actions

Appreciate the inputs.

CTRL-ALT-DEL is usually picked up by the Window Manager, or from console it is the reboot signal. A user cannot intercept that, see Control-Alt-Delete.

In general, a user process is not able to intercept the Control-Alt-Delete sequence.

Try this:

#!/usr/bin/perl
use warnings;
use strict;

sub handler_universal
{
  print "\ngot a signal $_[0]\n";
    $SIG{$_[0]} = \&handler_universal;
    }

my @nami = keys(%SIG);
#foreach( @nami){ print "$_\t$SIG{$_}\n"; }

while(1){
for my $namesig (@nami) {$SIG{$namesig} = \&handler_universal;}
}
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---

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

Your term - "failure cases" - is ambiguous. What you probably want to do is catch signals. See perldoc -q signals:

How do I trap control characters/signals?
       You don't actually "trap" a control character.  Instead, that c
+haracter generates a signal which is sent to your terminal's currentl
+y foregrounded process group,
       which you then trap in your process.  Signals are documented in
+ "Signals" in perlipc and the section on "Signals" in the Camel.

       You can set the values of the %SIG hash to be the functions you
+ want to handle the signal.  After perl catches the signal, it looks 
+in %SIG for a key with the
       same name as the signal, then calls the subroutine value for th
+at key.

               # as an anonymous subroutine

               $SIG{INT} = sub { syswrite(STDERR, "ouch\n", 5 ) };

               # or a reference to a function

               $SIG{INT} = \&ouch;

               # or the name of the function as a string

               $SIG{INT} = "ouch";

       Perl versions before 5.8 had in its C source code signal handle
+rs which would catch the signal and possibly run a Perl function that
+ you had set in %SIG.  This
       violated the rules of signal handling at that level causing per
+l to dump core. Since version 5.8.0, perl looks at %SIG *after* the s
+ignal has been caught, rather
       than while it is being caught.  Previous versions of this answe
+r were incorrect.
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Thats really nice help. Thank you onelesd.