RAR for MS DOS - If you are going to run RAR/DOS rar32.exe in Windows DOS box or command prompt, we strongly suggest to use rar.exe from WinRAR distributive instead. Rar.exe is also the command line tool and its command line syntax is practically the same as for DOS version, but unlike rar32.exe, rar.exe is a native Windows application, so it is more reliable and efficient when using in Windows. Also rar.exe provides a number of Windows specific options missing in DOS version.
You need to download RAR/DOS only if you are going to run it in OS/2 or real MS DOS, not just Windows DOS box.
