my $str = "The quick abc";

for my $regex ('\babc\z', '\babc\Z') {
    print "Matched with newline using $regex\n" if "$str\n" =~ $regex;
    print "Matched without newline using $regex\n" if $str =~ $regex;
}

##</code><code>##

Matched without newline using \babc\z
Matched with newline using \babc\Z
Matched without newline using \babc\Z