>>> with open('f.exe', 'w') as f:
...     f.write('hi')
...
>>> with open('f') as f:
...     print(f.read())
...
hi


`os.path.exists(...)` and others treat them as the same file as well.  It seems the only reliable way to write both files is:

1. write to f.exe
2. write to f.bak
3. move f.bak to f (`os.rename`)

ah yes, I should include more version information

IEUser@IE11WIN7 ~
$ python --version
Python 2.7.14

IEUser@IE11WIN7 ~
$ python3 --version --version
Python 3.6.4 (default, Jan  7 2018, 17:45:56)
[GCC 6.4.0]


IEUser@IE11WIN7 ~
$ uname -a
CYGWIN_NT-6.1 IE11WIN7 2.11.2(0.329/5/3) 2018-11-08 14:30 i686 Cygwin

This sounds like a Cygwin issue; what can Python do about it?

From a Cygwin shell:

$ ls

$ echo "test.exe" >> test.exe

$ echo "test" >> test

$ cat test
test.exe
test

hmmm probably nothing in that case -- didn't realize this also happened in the cygwin shell.

insanity.

feel free to close!  thanks!