$trigger='OFF';
my $pid = fork();
if ($pid == 0) {
#some process invoked on xterm
if (process invoked on xterm gives a signal){
        $trigger='ON';
}
exit 0;
}

my $pid = fork();
if ($pid == 0) {
#some other process on xterm
if( $trigger eq 'ON') {      #------->This has value OFF as declared globally. I want this to have value from previous process. What do I do?
           #do something
exit 0;
}