OPS245 Lab 3

!!!THIS LAB IS NOT READY YET!!!

In this lab we'll look at the simplest types of user management on a Linux system.

What's a user

• Look at the contents of the /etc/passwd file:

Every line in that file is a user. Two of them you have used explicitly: root and your own username.

Each line is made of several fields, delimited by a colon. The same as a comma-separated value file (CSV) but separated by colons instead of commas. The fields are:

• The username (e.g. asmith15)
• A field that's no longer used, in the distant past it was the user's password
• The UID (user ID) - a unique number identifying the user. The system uses these numbers to determine who owns which files and processes.
• The GID (group ID) - the number identifying the user's primary group. Every user on a Linux system is a member of at least one group. It can be a member of other groups as well, but that membership is specified in the /etc/group file.
• A comment - an unstructured string of text, usually used to store a user's full name.
• The user's home directory. It's a sort of default directory for each user. You'll have noticed that it's the directory your shell is in when you log in, and it's what ~ and $HOME are set to.
• The user's login shell. You would have only ever used Bash, but there are several other shells which some people prefer. The differences mostly matter only to advanced users.