It is incorrect to use: rc = subprocess.call(["ls", "-l"], shell=True) It means a different thing. OP should use either: rc = subprocess.call(["ls", "-l"

It is incorrect to use: rc = subprocess.call(["ls", "-l"], shell=True) It means a different thing. OP should use either: rc = subprocess.call(["ls", "-l"]) Or: rc = subprocess.call("ls -l", shell=True) Note: there is no need to use the shell or even to use the external processs in this case. The example shows the usability issue in the API. Newly designed C++ API shouldn't copy such errors (if it has the same behavior). A list argument with shell=True should be rejected.