Is the following expected? $ for impl in python{2.7,3.{3,4,5}}; do ${impl} -c "import sysconfig; print(sysconfig.get_config_var('SOABI'))"; done None cpython-33m cpython-34m cpython-35m-x86_64-linux-gnu
Yes.
See how extensions are named.
The change to the extension module file names is described here. https://docs.python.org/3/whatsnew/3.5.html#build-and-c-api-changes From configure.ac: SOABI='cpython-'`echo $VERSION | tr -d .`${ABIFLAGS}${PLATFORM_TRIPLET:+-$PLATFORM_TRIPLET} PLATFORM_TRIPLET is set based on cpp test. > ... > # if defined(__x86_64__) && defined(__LP64__) > x86_64-linux-gnu > # elif defined(__x86_64__) && defined(__ILP32__) > x86_64-linux-gnux32 > # elif defined(__i386__) > i386-linux-gnu > ...