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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