Just a text file? DOS, *nix, and Mac all use ASCII text files. The only difference is in the line endings:

# DOS/Win32
print "Hello, world!\r\n";

# *nix
print "Hello, world!\n";

# Mac
print "Hello, world!\r";
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MacOS X also uses "\n" for console programs.

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Reinvent a rounder wheel.

Note: All code is untested, unless otherwise stated