None of those work in Windows. (I presume that's what you meant by DOS.) 
>echo Hello > winfile.txt

>echo World >> winfile.txt

>perl -pe "s/\r(?=\n)//" winfile.txt > unixfile.txt

>debug unixfile.txt
-rcx
CX 0010
:
-d100 l10
0AF7:0100  48 65 6C 6C 6F 20 0D 0A-57 6F 72 6C 64 20 0D 0A   Hello ..W
+orld ..
-q

[download]

Well, they might work with a simulated unix environment in Windows (like cygwin), but that's an entirely different world.

The earlier posts in this thread not only provided the solution, they explained this problem and the workaround.

If it's one-liners you wanted,

In reply to Re^2: Remove CR from file on Windows by ikegami
in thread Remove CR from file on Windows by kp

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