how to get program files x86 env variable?

On a 64-bit machine running in 64-bit mode:

• echo %programfiles% ==> C:\Program Files
• echo %programfiles(x86)% ==> C:\Program Files (x86)

On a 64-bit machine running in 32-bit (WOW64) mode:

• echo %programfiles% ==> C:\Program Files (x86)
• echo %programfiles(x86)% ==> C:\Program Files (x86)

On a 32-bit machine running in 32-bit mode:

• echo %programfiles% ==> C:\Program Files
• echo %programfiles(x86)% ==> %programfiles(x86)%

Another relevant environment variable is:

%ProgramW6432%

So, on a 64-bit machine running in 32-bit (WOW64) mode:

• echo %programfiles% ==> C:\Program Files (x86)
• echo %programfiles(x86)% ==> C:\Program Files (x86)
• echo %ProgramW6432% ==> C:\Program Files

From Wikipedia:

The %ProgramFiles% variable points to the Program Files directory, which stores all the installed programs of Windows and others. The default on English-language systems is "C:\Program Files". In 64-bit editions of Windows (XP, 2003, Vista), there are also %ProgramFiles(x86)%, which defaults to "C:\Program Files (x86)", and %ProgramW6432%, which defaults to "C:\Program Files". The %ProgramFiles% itself depends on whether the process requesting the environment variable is itself 32-bit or 64-bit (this is caused by Windows-on-Windows 64-bit redirection).

Reference: http://en.wikipedia.org/wiki/Environment_variable