To substitute Macintosh (\cM), DOS (\cM\cJ) and Unix (\cJ) linefeeds, use s/\r\n?|\n/(something)/g.
If you just want to remove them, tr/\cM\cJ//d is a lot faster.

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$
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