Win8 Strawberry 5.8.9.5 (32)  Thu 07/15/2021 13:10:20
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings
my $file="Billy_Bob_Smith";
$file =~ s/_/\\_/g;
print "'$file' \n";

use Data::Dumper;
print Dumper $file;
^Z
'Billy\_Bob\_Smith'
$VAR1 = 'Billy\\_Bob\\_Smith';