How to allow users to create and delete file(s) / folder(s), but not modify them?

Question

I have created a group name "app-data" and a folder /db-data/archived-data/

I want members of app-data to have all rights on /db-data/ folder but I want the same group users have only create and delete access on /db-data/archived-data/ folder (users should not be able to modify any files or directories in it. but they should be able to create or delete any files or folders they want.

How can we do it. I think this is possible through ACL but please feel free to let me know how can we achive this? using any method I am fine but I want this configuration.

please help.

Answer 1

This is definitely possible. First, change /db-data's group to app-data:

sudo chgrp -R app-data /db-data

Now set up the permissions:

sudo chmod -R g+rwx /db-data
sudo chmod -R g-w /db-data/archived-data/*
sudo find /db-data/archived-data -type d -exec 'chmod' 'g+rwx' '{}' ';'

• sudo chmod -R g+rwx /db-data gives app-data full permissions to /db-data and everything inside it
• sudo chmod -R g-w /db-data/archived-data/* removes app-data's write permissions for everything inside /db-data/archived-data
• Finally, sudo find /db-data/archived-data -type d -exec 'chmod' 'g+rwx' '{}' ';' restores app-data's write permissions for every directory in /db-data/archived-data (but not the files inside those directories), which is necessary to let app-data create and delete any files or directories inside /db-data/archived-data.

Now anyone in app-data will be able to read, execute, create, and delete files or directories in /db-data/archived-data (including sub-directories deeper than 1 level; i.e. app-data will be able to create and delete files in /db-data/archived-data/a/b/). If you don't want app-data to have read and/or execute permissions either, change the g-w in sudo chmod -R g-w /db-data/archived-data/* to g-rw for no read permissions, g-wx for no execute permissions, or g-rwx for no permissions at all (if you do this after running the find command, you will have to re-run it).

Finally, note that if a user in app-data creates a file or directory, he/she will be able to modify the file/directory that he/she created (but existing files will still be unmodifiable).