`os.symlink` vs `ln -s`

Question

I need to create a symlink for every item of dir1 (file or directory) inside dir2. dir2 already exists and is not a symlink. In Bash I can easily achieve this by:

ln -s /home/guest/dir1/* /home/guest/dir2/

But in python using os.symlink I get an error:

>>> os.symlink('/home/guest/dir1/*', '/home/guest/dir2/')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: [Errno 17] File exist

I know I can use subprocess and run ln command. I don't want that solution.

I'm also aware that workarounds using os.walk or glob.glob are possible, but I want to know if it is possible to do this using os.symlink.

Answer 1

* is a shell extension pattern, which in your case designates "all files starting with /home/guest/dir1/".

But it's your shell's role to expand this pattern to the files it matches. Not the ln command's.

But os.symlink is not a shell, it's an OS call - hence, it doesn't support shell extension patterns. You'll have to do that work in your script.

To do so, you can use os.walk, or os.listdir. As indicated in the other answer, the appropriate call will depend on what you want to do. (os.walk wouldn't be the equivalent of *)

---

To convince yourself: run this command on an Unix machine in your terminal: python -c "import sys; print sys.argv" *. You'll see that it's the shell that's doing the matching.

Answer 2

As suggested by @abarnert it's the shell that recognizes * and replaces it with all the items insside dir1. Therefore I think using os.listdir is the best choice:

for item in os.listdir('/home/guest/dir1'):
    os.symlink('/home/guest/dir1/' + item, '/home/guest/dir2/' + item)