先把 stderr 重定向到 stdout 里，看一下是程序内部报错，还是环境问题，
参考：
https://stackoverflow.com/questions/16198546/get-exit-code-and-stderr-from-subprocess-call
参考：
https://stackoverflow.com/questions/16198546/get-exit-code-and-stderr-from-subprocess-call
shell=True 可能不需要，根据你原先代码来改
“`
try:
output = subprocess.check_output(
cmnd, stderr=subprocess.STDOUT, shell=True, timeout=3,
universal_newlines=True)
except subprocess.CalledProcessError as exc:
print(“Status : FAIL”, exc.returncode, exc.output)
else:
print(“Output: \n{}\n”.format(output))
“`
