Linux Tutorial Series – 123 – Review

Here is the video version, if you prefer it:

We talked about file modes and permissions. Let’s review that on an example:

-rw-r--r--

First character (looking from left to right) tells us if we are talking about a file or a directory or something else, the next three characters tell us user permissions, the next three tell us group permissions and the next three tell us world permissions.

Then we talked about the following:

• chmod is used to change file permissions
• chown is used to change file owner
• umask defines the default permissions (keep in mind the octal to binary conversion we talked about and how it relates to permissions)
• passwd is used to change users password
• adduser is used to add users
• userdel command is used to delete users
• /etc/passwd keeps users and their IDs, while /etc/sudoers keeps the list of users who can execute the sudo command

Hope you refreshed your memory!