You say your code "like" this:

  $pid=fork();
  exec("notepad");
  $SIG{INT}=\&handler;
  sub handler { kill 1,$pid; }
[download]

So I tried:

  my $pid = fork() ;  die "fork failed '$!'" if !defined($pid) ;

  if ($pid == 0) { exec("notepad") ; } ;

  print "Started Notepad \$pid = $pid\n" ;

  my $r = 1 ;

  sub handler { kill 'INT', $pid ; $r = 0 ; } ;

  $SIG{INT}=\&handler;

  while ($r) { sleep(1) } ;

  print "And we're done\n" ;
[download]

I could not find a way of discovering the pid of the process created by the exec -- and system doesn't do the trick either....

But I did find Win32::Process, and the following appears to work:

  use strict ; use warnings ;

  use Win32::Process ;
  use Win32 ;

  my $SystemRoot = $ENV{SystemRoot} ;
  print "\$SystemRoot = '$SystemRoot'\n" ;

  sub ErrorReport{
    print Win32::FormatMessage( Win32::GetLastError() );
  }

  my $ProcessObj ;
  Win32::Process::Create($ProcessObj,
                         "$SystemRoot\\notepad.exe",
                         "notepad",
                         0,
                         NORMAL_PRIORITY_CLASS,
                         "."
                        )                 or die ErrorReport() ;

  my $pid = $ProcessObj->GetProcessID() ;

  print "Started Notepad \$pid = $pid\n" ;

  my $run = 1 ;
  sub handler { $ProcessObj->Kill(1234) ; $run = 0 ; } ;

  $SIG{INT}=\&handler;

  while ($run) { sleep(1) } ;

  print "And we're done\n" ;
[download]

Use system instead of fork and exec.
(Sorry Anonymous Monk, but I can't \msg you to do an update)

i tried system,but it is not closing the notepad.Whether i have to make any changes in the kill statement?