#!/usr/bin/perl
use strict;
use warnings;

my $string = '\.foo';

print $string, "\n";

for (1..3) {
    # Note the concatenation instead of re-quotemeta-ing
    $string .= quotemeta "*[$_]";
    print $string, "\n";
}


__END__
# prints:
\.foo
\.foo\*\[1\]
\.foo\*\[1\]\*\[2\]
\.foo\*\[1\]\*\[2\]\*\[3\]