[sagittarius:~]$ md5sum *cmd.exe
5746bd7e255dd6a8afa06f7c42c1ba41 system32-cmd.exe
ad7b9c14083b52bc532fba5948342b98 syswow64-cmd.exe

However, I was still right about one thing: If you examine the output of Windows’ task manager, cmd.exe from System32 appears as a native app; running cmd.exe from SysWoW64 will flag it with the “*32″ suffix indicating that it’s running under 32-bit emulation.

My conclusion is different: It is feasible (although Windows isn’t really my native OS) that the reason some people had success with the SysWoW64 version because of some weirdness in the emulation layer that running a 32-bit version of cmd.exe would fix.

Please disregard my previous post, at least partially. Cygwin clearly didn’t report the correct information to me, and I didn’t bother to double check it.

Either way, Sid’s original post was spot on. So bear in mind: If you’re running cmd.exe from SysWoW64, you are running the *32-bit* version, NOT 64-bit as some other posters have indicated. The MD5 sum of the 32-bit version should be ad7b9c14083b52bc532fba5948342b98, which you can verify yourself.

Two nitpicks with everyone claiming that the SysWoW64 version is necessary: 1) SysWoW64 is the “Windows 32-bit on Windows 64-bit” subsystem and this location contains Windows 32-bit on 64-bit helpers (see the Wikipedia article for references). 2) There is no functional difference between the cmd.exe contained in System32 versus the one in syswow64. They are identical (md5sum from a Cygwin shell), and here’s proof:

bshelton@/cygdrive/c/windows/syswow64$ md5sum cmd.exe
ad7b9c14083b52bc532fba5948342b98 *cmd.exe

bshelton@/cygdrive/c/windows/syswow64$ md5sum ../system32/cmd.exe
ad7b9c14083b52bc532fba5948342b98 *../system32/cmd.exe

Furthermore, Cygwin reports cmd.exe as a 32-bit binary:

bshelton@/cygdrive/c/windows/system32$ file cmd.exe
cmd.exe: PE32 executable (console) Intel 80386, for MS Windows

Compared to others which appear to be 64-bit:

bshelton@/cygdrive/c/windows$ file write.exe
write.exe: PE32+ executable (GUI) x86-64, for MS Windows

So to put this to rest: Regardless of which cmd.exe you’re running, you are running identical files, both of which appear to be built for the x86 architecture. If you’re having difficulty with one, it’s exceedingly likely that you haven’t properly elevated the command prompt’s permissions and has nothing to do with the target arch (in fact it can’t!).