Share some folder with multiple users and allow all of them to read and write without sudo everytime

# Create group
sudo groupadd data-dir-write

# Add users to group
sudo usermod -a -G data-dir-write user1
sudo usermod -a -G data-dir-write user2

# Assign group to that directory
sudo chgrp -R data-dir-write /shared-dir

# add write permission to group
sudo chmod -R g+w /shared-dir

# To Preserve group permissions afterwards
sudo chmod g+s /shared-dir

# To preserve group permission on subfolders recursively
sudo find ./shared-dir -type d -exec chmod g+s {} \;

# Don't forget to logout and login again for final test

💡 Still getting permission denied?
verify it by running ls -lth and then ensure that directory has drwxrwsr-x