Linefeed/carriage return matching

Hi,

I'm a newbie regular expression user here and I need experts' help!! I need
to have a Perl style regular expression that can match a string with either
Mac style or PC style linefeed/carriage return in it. On Mac I believe you
only have CR character and PC has CRLF as the way to represent the [Return].

For example, I might have this:

This is a
text

Where on Mac, it is actually represented as
This is a<CR>text

Where if it's on PC it would be
This is a<CR><LF>text

I need to find a regular expression that matches the string across the
platform where it basically ignores everything but the carriage return and
line feed characters. I've read through the online documentation and saw /s
modifier and thought I should be able to combine that with (.+?) to match
either <CR> and/or <LF> but honestly don't know how to combine those
elements. 

Thanks for the help!!!

Ryo