/etc/passwd This is a very important file on your system! It's used to keep track of all users on the system. Run cat /etc/passwd and look at the output; each line is organized in this format:
username:password:UID:GID:UID info:home directory:command/shell
Let’s run through what each of those mean:
username: the user’s login name password: the password, will simply be an x if it’s encrypted user ID (UID): the user’s ID number in the system. 0 is root, 1-99 are for predefined users, and 100-999 are for other system accounts group ID (GID): Primary group ID, stored in /etc/group. user ID info: Metadata about the user; phone, email, name, etc. home directory: Where the user is sent upon login. Generally /home/ command/shell: The absolute path of a command or shell (usually /bin/bash).