Question

I need to call an executable in a python script and also pass binary data (generated in the same script) to this executable.

I have it working like so:

bin = make_config(data)
open('binaryInfo.bin', 'wb+').write(bin)

os.system("something.exe " + "binaryInfo.bin")

I thought I could avoid creating the binaryInfo.bin file altogether by passing ‘bin’ straight to the os.system call:

bin = make_config(data)

os.system("something.exe " + bin)

But in this case I get an error:
“Can’t convert ‘bytes’ object to str implicitly”

Does anyone know the correct syntax here? Is this even possible?

Answer 1

Does anyone know the correct syntax here? Is this even possible?

Not like you’re doing it. You can’t pass arbitrary binary data on the UNIX command line, as each argument is inherently treated as null-terminated, and there’s a maximum total length limit which is typically 64KB or less.

With some applications which recognize this convention, you may be able to pipe data on stdin using something like:

pipe = os.popen("something.exe -", "w")
pipe.write(bin)
pipe.close()

If the application doesn’t recognize “-” for stdin, though, you will probably have to use a temporary file like you’re already doing.