Why doesn’t chmod under Bash on Ubuntu on Windows 10 actually “take”?

I’m continuing to beat my head against a wall, attempting to test a very simple configuration change to an Ansible playbook I wrote, so that I can verify if my understanding of the use of Ansible vault is correct.

The latest problem?  Unix permissions.

Now that I’ve got SSH communications working between by Bash shell (Ubuntu on Windows 10, aka WSL), I’ve implemented changes to the playbook’s files including creating a .vault_pass.txt file under the Bash shell, and encrypting a vault.yml file using the password contained in the .vault_pass.txt.

When I run ansible-playbook role.yml –vault-password-file .vault_pass.txt, it complains of the following:

mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ ansible-playbook role.yml --vault-password-file .vault_pass.txt
ERROR! Problem running vault password script / m n t / c / U s e r s / M i k e / c o d e / C o p y - a n s i b l e - r o l e - u n a t t e n d e d - u p g r a d e s / . v a u l t _ p a s s . t x t ([Errno 8] Exec format error). If this is not a script, remove the executable bit from the file.

No problem, I’ve got this.  Just gotta run chmod 600 (or similarly, to remove the execute bit for my user) on the .vault_pass.txt file.  [For comparison, I just tried this on the same configuration under Ubuntu – which is having a different blocking issue at present, but not related to file permissions – and the command took immedateily.]  Hah, you should be so lucky:

mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ ls -la .vault_pass.txt
-rwxrwxrwx 1 root root 25 Sep 26 18:38 .vault_pass.txt
mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ chmod 600 .vault_pass.txt
mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ ls -la .vault_pass.txt
-rwxrwxrwx 1 root root 25 Sep 26 18:38 .vault_pass.txt
mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ whoami
mike
mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ sudo chmod 600 .vault_pass.txt
[sudo] password for mike:
mike@MIKE-WIN10-SSD:~/code/ansible-role-unattended-upgrades$ ls -la .vault_pass.txt
-rwxrwxrwx 1 root root 25 Sep 26 18:38 .vault_pass.txt

Yes, I get that the file is owned by root, and I’m running as mike – so why doesn’t it make a difference when I run sudo chmod?  Is this a problem with files owned by root?  Is this a problem with chmod?  Is this a problem with WSL/Bash?

Lightbulb moment

I went hunting for such issues in the Microsoft repo for the Bash On Windows project, and found this issue & comment:

https://github.com/Microsoft/BashOnWindows/issues/81#issuecomment-207553514

So I figured I re-examine the situation.  All my files under the ~/code folder are owned by root – even . and .., which is odd…

mike@MIKE-WIN10-SSD:~/code$ ls -la
total 68
drwxrwxrwx 2 root root 0 Sep 26 10:51 .
drwxrwxrwx 2 root root 0 Aug 16 17:00 ..
drwxrwxrwx 2 root root 0 Aug 16 16:28 ansible-role-unattended-upgrades

Then I looked at my home folder and – d’oh!

mike@MIKE-WIN10-SSD:~$ ls -la
total 24
drwxr-xr-x 2 mike mike 0 Sep 26 18:37 .
drwxr-xr-x 2 root root 0 Dec 31 1969 ..
-rw------- 1 mike mike 2452 Aug 16 22:48 .bash_history
-rw-r--r-- 1 mike mike 220 Aug 5 10:06 .bash_logout
-rw-r--r-- 1 mike mike 3637 Aug 5 10:06 .bashrc
lrwxrwxrwx 1 mike mike 22 Aug 16 12:58 code -> /mnt/c/Users/Mike/code

Idiot.

Now I remember: when I first sat down with this Bash On Ubuntu on Windows setup, I figured I’d save myself some trouble by using the exact same files in all my local repos – why bother duplicating the repos between Windows and Bash on Ubuntu?  So I symlinked a mount of the /code folder from my Windows user profile…and left myself a nice little landmine, it seems.

Rather than struggle with cacls.exe and try to find some magic combination that results in non-executable permissions on that file through the WSL translation layer (if at all), I just cloned the repo to a different folder (local to the Bash/Ubuntu/Win10 environment) and retried, with trivial success.

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