Alex W.'s Blog

Supporting CLI programs in `` on macOS & Windows without `shell=True`

In Windows, uses CreateProcess (docs) which (appears to?) only identify .exe files by default. Therefore when trying to run something like the heroku CLI using'heroku') it fails with [WinError 2] The system cannot find the file specified. Using where heroku I can see that it has two executables at:

C:\Program Files\heroku\bin\heroku
C:\Program Files\heroku\bin\heroku.cmd

Using shell=True fixes this because the shell (cmd.exe /c) resolves these paths, while CreateProcess doesn’t. However, I can resolve these using another Python tool and avoid introducing the security issues and overhead of shell=True by using the shutil.which method (docs).

Combined, the full command would be:'heroku'))

Written by Alex Wendland, who is currently exploring fintech at Pinwheel. Here's a Twitter handle, a GitHub, some LinkedIn, ol' Facebook, or a hip Instagram if you're interested.