$ perl -E 'my $x = qq{qwerty\n}; $re = qr{\Aqwerty\Z}; say +($x =~ /$re/) ? 1 : 0;'
1
$ perl -E 'my $x = qq{qwerty\n}; $re = qr{\Aqwerty\z}; say +($x =~ /$re/) ? 1 : 0;'
0