Regex : Anchors and the /m modifier

Anchors
^ matches at the start of a string
$ matches at the end of a string

$x = /andrew/

$x =~ /^a/ ;
# matches as andrew starts with an a

$x =~ /rew$/;
# matches as andrew ends with a rew

But what if you have a string containing several lines (e.g. a file with \n characters) ?

The /m modifier.

This treats the string as multiple lines, so ^ and $ will match the start and end of each line in the file

$x = qq(
andrew
john andrew
andrew
);
$x =~ s/^andrew/ANDREW/mg;
# will replace 1st and 3rd andrew
# without the /m, it would only replace the third
This treats the string as a single line, so