subprocess : FileNotFound

Question

Could someone explain this error to me :

>>> def j():
...     import subprocess
...     print(subprocess.Popen(['command', '-v', 'nmcli'],     stdout=subprocess.PIPE, stderr=subprocess.PIPE))
... 
>>> j()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in j
File "/usr/lib/python3.4/subprocess.py", line 859, in __init__
restore_signals, start_new_session)
File "/usr/lib/python3.4/subprocess.py", line 1457, in _execute_child
raise child_exception_type(errno_num, err_msg)
FileNotFoundError: [Errno 2] No such file or directory: 'command'

I tried as a string as a list, it does not change anything.

Thank you,

Answer 1

FileNotFoundError: [Errno 2] No such file or directory: 'command'

command is a shell builtin. subprocess.Popen does NOT run the shell by default.

To run the shell, pass shell=True:

>>> import subprocess
>>> subprocess.check_output('command -v python', shell=True)
b'/usr/bin/python\n'

To find the full path to an executable, you could use shutil.which() instead:

>>> import shutil
>>> shutil.which('python')
'/usr/bin/python'