$x = "There once was a girl\nWho programmed in Perl\n"; 
$x =~ /^Who/; # doesn't match, "Who" not at start of string 
$x =~ /^Who/s; # doesn't match, "Who" not at start of string 

$x =~ /^Who/m; # matches, "Who" at start of second line <----

$x =~ /^Who/sm; # matches, "Who" at start of second line 
$x =~ /girl.Who/; # doesn't match, "." doesn't match "\n" 
$x =~ /girl.Who/s; # matches, "." matches "\n" 
$x =~ /girl.Who/m; # doesn't match, "." doesn't match "\n" 
$x =~ /girl.Who/sm; # matches, "." matches "\n"

##</code><code>##

$x =~ /^Who/m;   # matches, "Who" at start of second line
$x =~ /\AWho/m;  # doesn't match, "Who" is not at start of string
$x =~ /girl$/m;  # matches, "girl" at end of first line
$x =~ /girl\Z/m; # doesn't match, "girl" is not at end of string
$x =~ /Perl\Z/m; # matches, "Perl" is at newline before end
$x =~ /Perl\z/m; # doesn't match, "Perl" is not at end of string