如何知道和防止来自 python 的终端命令出错？

Question

Making a program which can open apps upon listening to commands. The app name is stored in variable 'a'. And then opened with the following line:

os.system("open /Applications/" + a + ".app")

But sometimes it is possible that 'a' does not exist on the system, say 'music' for which the console prints:

The file /Applications/music.app does not exist.

And the python code stops entirely.

How can I know that the console gave this error and prevent the program from stopping?

Answer 1

subprocess is more powerful than os.system , the stdout and stderr of subprocess can be ignored with subprocess

import subprocess
res=subprocess.run(["open", "/Applications/" + a + ".app"])
print(res.returncode)

use res.returncode to get the execute result(none zero value shows that the sub process has encountered errors).

Answer 2

Maybe you could try to use the try / except commands to handle errors in python: https://docs.python.org/3/tutorial/errors.html .