Maybe add ".CMD" to this list? And make the documentation more explicit that the file extensions are appended to the input?

[josiahdj]

https://github.com/fsharp/FAKE/blob/7f99a9c4350b6b15a044254977c882574cd72b61/src/app/Fake.Core.Process/Process.fs#L622

In my case, it took me a while to track down why this wasn't finding "grunt.cmd" the way it used to in FAKE 4 (for Windows). Simple fix in my build script was to remove the ".cmd", so I "fixed it" for myself, but this could confuse other people?

[matthid]

Is the PATHEXT variable not defined on your system?

[josiahdj]

It is, and I got it to work once I removed the .cmd at the end of the command (grunt.cmd) I wanted. Maybe a good way of handling this is:
if Environment.isWindows and the end of the file given already contains one of the extensions listed in PATHEXT, then don't re-append the postFix values from the PATHEXT in the call to Seq.tryPick?

[matthid]

Ah now I get it. You basically suggest doing a search with empty "suffix" first. Yes that sounds reasonable.

I guess for cross platform compatibility we assume users don't specify the file-extension there

[josiahdj]

LGTM