Verboser output of child in case of invalid/unknown command

[ghost]

We are currently validating various libs for a simple process handling in C++ (came from Boost.Process...) and are quite excited about subprocess.h

However, when doing some basic tests we might have found a part of the lib, which could be improved to ease troubleshooting for the user/developer.
E. g. when somebody gives an invalid command (e.g. lss) no further information is given. In contrast, other libs give some hint in the form of execv's perror message or a dedicated error code. In case you are interested i appended you our patch file. With this update it is possible to check the child's stdout/stderr for the error message or simply provide it to the user.

If you have any further questions please feel free to ask.

subprocess.perror.patch.txt

[ghost]

Updated the patch. Maybe the best approach would be to forward a dedicated error code to the parent?

subprocess.perror.patch.txt

[sheredom]

Hey there! Any chance you've got a dumb test case with the output you get with this patch? I just want to understand what is being reported back to the user with it, so I can guage how to make this work nicer.