Group

Ubuntu Privilege: Group

Add group: groupadd

You can create a whole new system group and control the user’s privileges by using the group.

groupadd <group-name>

Check user group

groups user1
user1 : <other-groups> www-data
getent group www-data
www-data:x:33:kejyun,group1

getent group www-data  | awk -F: '{print $4}'
kejyun,group1

Add user to a specific group

Using command to add user to a group

sudo adduser $USER www-data

Edit group file to add user to a group

sudo vim /etc/group

There is di

Add the specific user to the group at end of group. Seperated each user by commas.

www-data:x:33:kejyun,group1,group2

Add user with sudo root privileges

sudo adduser 帳號名稱 sudo

Change file group

No one can change the file owner to another user except root account. So if you want to change the file group. You must add the sudo in front of your command.

Non-privileged users (not root) cannot chown files to other user names. To use chown, a user must have the privileges of the target user. In other words, only root can give a file to another user.

sudo chown -R root:root ./folder

Reference