If you’re administering a Linux server, chances are you have a lot of user accounts to manage and, along with these, a lot of files and settings to control. Here are some commands and issues that are important in setting up and managing user accounts and access rights.
Dealing with IDs
First, in managing user accounts, you need to be aware of both user IDs (UID) and group IDs (GID). Most accounts are set up with each user being the sole member of a group that has the same name as the user’s account. In fact, both are set up when an account is created using the useradd command. When you list a user’s home directory, you should see something like this:
Source:: Network World – Data Center