Regex modifiers

/m    (^) ... ($)  \n  (^) ... ($)
/s    (^) ...  $  (\n)  ^  ... ($)
/ms   (^) ... ($) (\n) (^) ... ($)

         (\A) ... \n ... (\Z) \n
         (\A) ... \n ...     (\z)


###
havoc without [ms]:

#!/usr/bin/perl

$str = "abc\ndef\nghi";

print 'NO [m] [s]: ';
if ( $str =~ m/^(\w{1}).*(\w{1})$/ )
{
        print "$1::$2";
}
print "\n";


print '[m]: ';
if ( $str =~ m/^(\w{1}).*(\w{1})$/m )
{
        print "$1::$2";
}
print "\n";


print '[s]: ';
if ( $str =~ m/^(\w{1}).*(\w{1})$/s )
{
        print "$1::$2";
}
print "\n";

# s/// is ok (/s by default)
print "[change]: \n";
$str =~ s/def//;
print "$str\n";