print "Delete this file?[n]: ";
chomp(my $answer=<STDIN>);
if ($answer=~/^y|yes$/i){
    unlink $file or die $!;
} elsif ($answer=~/^n|no|$/i){
        next;
} else { .....

##</code><code>##

prompt?
accept: y,n,yes,no
default: to one of the above
continue with program flow