The following code should do the trick:

use strict;
use warnings;

use Config;
use List::MoreUtils qw(firstidx);

my @signals = split / /, $Config{sig_name};
my $rtmin = firstidx { $_ eq 'RTMIN' } @signals;
my $rt5name = $signals[ $rtmin + 5 ];
print "They call it $rt5name\n";

$SIG{$rt5name} = sub { warn "caught it!\n" };

sleep 10 while 42;
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