Difference between revisions of "Managing Ubuntu Linux Users and Groups"

Revision as of 14:48, 5 July 2007

Linux is a multi-user operating system. This means that more than one user can be actively logged and using the system at any one time. Obviously, it makes sense for each user to have their own user account and home directory, and for different users to have different privileges.

Users are further divided into groups for the purposes of easier administration and those groups can have different levels of privileges. For example, you may have a group of users who work in the Accounting department. In such an environment you may wish to create an accounts group and assign all the the Accounting department to that group.

In this chapter we will cover the steps to add, remove and manage users and groups on an Ubuntu Linux system.

Adding a User to an Ubuntu Linux System

There are two methods for adding new users to a system, one way is using the graphical User Settings tool and the other is to use the adduser command-line tool. In this section we will look at both approaches.

To add a new user to your Ubuntu Linux system using the User settings tool select System desktop menu and choose Users and Groups from the Administration sub-menu. A dialog similar to the one shown below will appear:

To add a new user click on the Add User button. The New user account dialog will subsequently appear ready to be filled in with data relating to the new user, such as username, real name, password and contact information:

To define the privileges for this new user select the Privileges tab of the New user account dialog to display the privileges screen:

De-select any privileges you do not wish the new user to have. In particular you will want to ensure the user does not have Administration privilege unless the user is a trusted system administrator. The other privileges are usually considered to be safe for the typical user.

The final screen on the Add user dialog allows Advanced settings to be defined. These include such issues as the home directory of the user (traditionally /usr/username), tyhe type of shell that is presented as the command line in a terminal window (Bash is usually tyhe default), the group to which the user belongs and the user ID. Use the drop down group menu to change the user's group membership to a different group:

Once the new user is configured, click on the OK button to add the new user. Once added the new user should appear in the list of users in the settings dialog and it should be possible to login in using the username and password specified.

As mentioned above it is also possible to add new users from the command-line. To do so startt up a terminal widnow session and at the command prompt enter a command similar to:

sudo adduser --home /home/john john

The above command will prompt for a passowrd for the account and optional contact information. Once the information has been gathered adduser creates the new account and the /home/john home directory. adduser provides a number of different options which can be learned from the man page:

man adduser

Editing the Properties of a User

The properties of a user may be changed using the same User settings dialog used to add a user as outlined above. Select the System desktop menu and choose Users and Groups from the the Administration sub-menu to launch the User settings dialog. To make changes to the user properties select the user from the list and click on Properties. Work the various screens in the Account Properties for the selected user and click on the OK button to apply the changes

Deleting a User from an Ubuntu Linux System

An existing user may be deleted using the same User settings dialog used to add a user as outlined above. Select the System desktop menu and choose Users and Groups from the the Administration sub-menu to launch the User settings dialog.

Select the user to be deleted and click on Delete. A confirmation dialog will appear. If you wish to proceed click on Delete.

Note that the deletion process will remove the account but leave the user's home directory intact. This will need to be deleted manually if it, and any files therein, are no longer required.

A user account may also be deleted from command-line using the deluser utility:

sudo deluser john

It is also possible to remove the user's home directory as part of the deletion process:

sudo deluser --remove-home john

Alternatively all files owned by the user, including those in the user's home directory may be removed as follows:

sudo deluser --remove-all-files john

Adding a New Group to an Ubuntu Linux System