What is the difference between:
sudo chown $USER:$USER
and
sudo chown $USER
Why is it 2 times? Is the one user wrong? When I look at permissions with namei -l, I often see things like root root or proxy proxy.
Why does the owner have to be defined and listed 2 times?
The chown command is used to change the owner and group owner of a file or directory.
Superuser privileges are required to use this command. The syntax of chown looks like
this:
chown [owner][:[group]] file...
chown can change the file owner and/or the file group owner depending on the first argument of the command. Here are some examples:
chown owner file example:
chown bob file --> Changes the ownership of the file from its current owner to user bob.
chown owner:group file example:
chown bob:users file --> Changes the ownership of the file from its current owner to user bob and changes the file group owner to group users.
chown :group file example:
chown :admins file --> Changes the group owner to the group admins. The file owner is unchanged.
chown owner: file example:
chown bob: file --> Change the file owner from the current owner to user bob and changes the group owner to the login group of user bob.
Please read this nice tutorial https://www.linode.com/docs/tools-reference/linux-users-and-groups. This show some info about user, groups ,permissions ,...
