System accounts are used to run services such as DNS, mail, and web servers. The reason for this is security; if all services ran as the superuser, they could act without restriction.

Examples of system accounts are daemon, operator, bind, news, and www.

nobody is the generic unprivileged system account. However, the more services that use nobody, the more files and processes that user will become associated with, and hence the more privileged that user becomes.

User accounts are assigned to real people and are used to log in and use the system. Every person accessing the system should have a unique user account. This allows the administrator to find out who is doing what and prevents users from clobbering the settings of other users.

Each user can set up their own environment to accommodate their use of the system, by configuring their default shell, editor, key bindings, and language settings.

Every user account on a FreeBSD system has certain information associated with it:

The superuser account, usually called root, is used to manage the system with no limitations on privileges. For this reason, it should not be used for day-to-day tasks like sending and receiving mail, general exploration of the system, or programming.

The superuser, unlike other user accounts, can operate without limits, and misuse of the superuser account may result in spectacular disasters. User accounts are unable to destroy the operating system by mistake, so it is recommended to login as a user account and to only become the superuser when a command requires extra privilege.

Always double and triple-check any commands issued as the superuser, since an extra space or missing character can mean irreparable data loss.

There are several ways to gain superuser privilege. While one can log in as root, this is highly discouraged.

Instead, use su(1) to become the superuser. If - is specified when running this command, the user will also inherit the root user's environment. The user running this command must be in the wheel group or else the command will fail. The user must also know the password for the root user account.

In this example, the user only becomes superuser in order to run make install as this step requires superuser privilege. Once the command completes, the user types exit to leave the superuser account and return to the privilege of their user account.

% configure
% make
% su -
Password:
# make install
# exit
%

The built-in su(1) framework works well for single systems or small networks with just one system administrator. An alternative is to install the security/sudo package or port. This software provides activity logging and allows the administrator to configure which users can run which commands as the superuser.

The recommended program for adding new users is adduser(8). When a new user is added, this program automatically updates /etc/passwd and /etc/group. It also creates a home directory for the new user, copies in the default configuration files from /usr/share/skel, and can optionally mail the new user a welcome message. This utility must be run as the superuser.

The adduser(8) utility is interactive and walks through the steps for creating a new user account. As seen in Example 4.2, “Adding a User on FreeBSD”, either input the required information or press Return to accept the default value shown in square brackets. In this example, the user has been invited into the wheel group, allowing them to become the superuser with su(1). When finished, the utility will prompt to either create another user or to exit.

# adduser
Username: jru
Full name: J. Random User
Uid (Leave empty for default):
Login group [jru]:
Login group is jru. Invite jru into other groups? []: wheel
Login class [default]:
Shell (sh csh tcsh zsh nologin) [sh]: zsh
Home directory [/home/jru]:
Home directory permissions (Leave empty for default):
Use password-based authentication? [yes]:
Use an empty password? (yes/no) [no]:
Use a random password? (yes/no) [no]:
Enter password:
Enter password again:
Lock out the account after creation? [no]:
Username   : jru
Password   : ****
Full Name  : J. Random User
Uid        : 1001
Class      :
Groups     : jru wheel
Home       : /home/jru
Shell      : /usr/local/bin/zsh
Locked     : no
OK? (yes/no): yes
adduser: INFO: Successfully added (jru) to the user database.
Add another user? (yes/no): no
Goodbye!
#

To completely remove a user from the system, run rmuser(8) as the superuser. This command performs the following steps:

rmuser(8) cannot be used to remove superuser accounts since that is almost always an indication of massive destruction.

By default, an interactive mode is used, as shown in the following example.

# rmuser jru
Matching password entry:
jru:*:1001:1001::0:0:J. Random User:/home/jru:/usr/local/bin/zsh
Is this the entry you wish to remove? y
Remove user's home directory (/home/jru)? y
Removing user (jru): mailspool home passwd.
#

Any user can use chpass(1) to change their default shell and personal information associated with their user account. The superuser can use this utility to change additional account information for any user.

When passed no options, aside from an optional username, chpass(1) displays an editor containing user information. When the user exits from the editor, the user database is updated with the new information.

In Example 4.4, “Using chpass as Superuser”, the superuser has typed chpass jru and is now viewing the fields that can be changed for this user. If jru runs this command instead, only the last six fields will be displayed and available for editing. This is shown in Example 4.5, “Using chpass as Regular User”.

#Changing user database information for jru.
Login: jru
Password: *
Uid [#]: 1001
Gid [# or name]: 1001
Change [month day year]:
Expire [month day year]:
Class:
Home directory: /home/jru
Shell: /usr/local/bin/zsh
Full Name: J. Random User
Office Location:
Office Phone:
Home Phone:
Other information:

#Changing user database information for jru.
Shell: /usr/local/bin/zsh
Full Name: J. Random User
Office Location:
Office Phone:
Home Phone:
Other information:

Any user can easily change their password using passwd(1). To prevent accidental or unauthorized changes, this command will prompt for the user's original password before a new password can be set:

% passwd
Changing local password for jru.
Old password:
New password:
Retype new password:
passwd: updating the database...
passwd: done

The superuser can change any user's password by specifying the username when running passwd(1). When this utility is run as the superuser, it will not prompt for the user's current password. This allows the password to be changed when a user cannot remember the original password.

# passwd jru
Changing local password for jru.
New password:
Retype new password:
passwd: updating the database...
passwd: done

The pw(8) utility can create, remove, modify, and display users and groups. It functions as a front end to the system user and group files. pw(8) has a very powerful set of command line options that make it suitable for use in shell scripts, but new users may find it more complicated than the other commands presented in this section.