Python os.chdir（）到根目录实际上将目录更改为当前目录

Question

I am working on a project on path D:/code/project .

project.py

import os
import argparse

def create(path):
    if os.path.exists(path):
        os.chdir(path)
        app = open("app.py", "w+")
        app.write("print(\"Hello world!\")")
    else:
        path_list = path.split("/")
        for i in path_list:
            try:
                os.mkdir(i)
            except FileExistsError:
                pass
            except FileNotFoundError:
                print("Invalid path")
                exit()
            os.chdir(i)
        app = open("app.py", "w+")
        app.write("print(\"Hello world!\")")


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    create_parser = parser.add_subparsers().add_parser("create")
    create_parser.add_argument("path", nargs="?", default=".", metavar="path", type=str)
    args = parser.parse_args()
    create(vars(args)["path"])

Basically, it has a custom command called create which takes path as an argument. When it detects that path already exists, it will create a app.py at the directory specified, and if it does not, it will try and create the path and app.py .

However, when I run

D:/code/project> python project.py create D:/newpath

Instead of creating a new directory newpath under D: , it creates newpath under my current directory ( D:/code/project ).

How do I change it such that changing directory to a root directory will actually switch correctly?

Answer 1

Your issue is with this line:

path_list = path.split("/")

On windows, that doesn't correctly split the path. It leaves the drive letter 'D:' as a fragment all by itself, but when you try to change directory to that path, it does nothing (assuming the current directory was on D: somewhere). It is the same behavior you get with the cd command on a command prompt. Drive letters in paths are pretty weird, they don't work like normal path prefixes.

To correctly split the path, use os.path.split(path) . It will correctly use 'D:/' as the first element of the path, which when you change to it will put you on the root folder of your drive.

If you're using a recent version of Python (3.4+), you could also try using the pathlib module for a better, more object oriented way of manipulating paths:

from pathlib import Path

def create(path_str):
    path = Path(path_str)
    path.mkdir(parents=True, exist_ok=True)  # creates parent folders as needed
    with open(path / 'app.py', 'w') as app:  # / operator joins path fragments
        app.write('print("Hello world!")')