Eryk Sun added the comment:

difference from the behaviour of Posix's execvpe() was deliberate

POSIX doesn't define execvpe [1]. GNU glibc implemented it in 2009 [2]. On Windows, MSC has had execvpe and spawnvpe since at least 5.0 [3], and I think it arrived in 4.0 in 1986. Guido added os._execvpe in 1.2b4 [4] in 1995. I think it's the only implementation of execvpe that searches the passed environment. [1]: http://pubs.opengroup.org/onlinepubs/9699919799/functions/execvp.html [2]: https://sourceware.org/ml/libc-alpha/2009-10/msg00063.html [3]: https://openlibrary.org/works/OL2028669W [4]: https://hg.python.org/cpython/file/534a97c400cc/Lib/os.py ---------- nosy: +eryksun _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue15451> _______________________________________