[Tutor] Please correct my error handling

[Mats Wichmann]

On 1/2/20 11:12 AM, Robert Alexander wrote:
> I am having an hard time to properly address some errors in external
> programs launched by my python code.

Popen fails directly if it can't open a process for the requested 
command, so you have to check a different way for that case.  Try this:

> # 3) repeat with an illegal ;) command

try:
     process = subprocess.Popen(
             ['/bin/lsd', '-E'],
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
         )
except FileNotFoundError as e:
     print("--Command not found--\n", e)
     sys.exit(2)
     # or you could just "raise":

stdout, stderr = process.communicate()
if not stderr:
     print('--No errors--\n', stdout.decode())
else:
     print('--Error found--\n', stderr.decode())