There are a variety of different commands available in the UNIX® environment to manipulate user accounts. The most common commands are summarized below, followed by more detailed examples of their usage.
| Command | Summary |
|---|---|
| adduser(8) | The recommended command-line application for adding new users. |
| rmuser(8) | The recommended command-line application for removing users. |
| chpass(1) | A flexible tool to change user database information. |
| passwd(1) | The simple command-line tool to change user passwords. |
| pw(8) | A powerful and flexible tool to modify all aspects of user accounts. |
adduser(8) is a simple program for adding new users. It creates entries in the system passwd and group files. It will also create a home directory for the new user, copy in the default configuration files (“dotfiles”) from /usr/share/skel, and can optionally mail the new user a welcome message.
Example 13-1. Adding a user on FreeBSD
# 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]: 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! #
Note: The password you type in is not echoed, nor are asterisks displayed. Make sure that you do not mistype the password.
You can use rmuser(8) to completely remove a user from the system. rmuser(8) performs the following steps:
Removes the user's crontab(1) entry (if any).
Removes any at(1) jobs belonging to the user.
Kills all processes owned by the user.
Removes the user from the system's local password file.
Removes the user's home directory (if it is owned by the user).
Removes the incoming mail files belonging to the user from /var/mail.
Removes all files owned by the user from temporary file storage areas such as /tmp.
Finally, removes the username from all groups to which it belongs in /etc/group.
Note: If a group becomes empty and the group name is the same as the username, the group is removed; this complements the per-user unique groups created by adduser(8).
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, which attempts to make sure you know what you are doing.
Example 13-2. rmuser Interactive Account Removal
# 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 Updating password file, updating databases, done. Updating group file: trusted (removing group jru -- personal group is empty) done. Removing user's incoming mail file /var/mail/jru: done. Removing files belonging to jru from /tmp: done. Removing files belonging to jru from /var/tmp: done. Removing files belonging to jru from /var/tmp/vi.recover: done. #
chpass(1) changes user database information such as passwords, shells, and personal information.
Only system administrators, as the superuser, may change other users' information and passwords with chpass(1).
When passed no options, aside from an optional username, chpass(1) displays an editor containing user information. When the user exists from the editor, the user database is updated with the new information.
Note: You will be asked for your password after exiting the editor if you are not the superuser.
Example 13-3. Interactive chpass by Superuser
#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:
The normal user can change only a small subset of this information, and only for themselves.
Example 13-4. Interactive chpass by Normal User
#Changing user database information for jru. Shell: /usr/local/bin/zsh Full Name: J. Random User Office Location: Office Phone: Home Phone: Other information:
Note: chfn(1) and chsh(1) are just links to chpass(1), as are ypchpass(1), ypchfn(1), and ypchsh(1). NIS support is automatic, so specifying the yp before the command is not necessary. If this is confusing to you, do not worry, NIS will be covered in Chapter 29.
passwd(1) is the usual way to change your own password as a user, or another user's password as the superuser.
Note: To prevent accidental or unauthorized changes, the original password must be entered before a new password can be set.
Example 13-5. Changing Your Password
% passwd Changing local password for jru. Old password: New password: Retype new password: passwd: updating the database... passwd: done
Example 13-6. Changing Another User's Password as the Superuser
# passwd jru Changing local password for jru. New password: Retype new password: passwd: updating the database... passwd: done
Note: As with chpass(1), yppasswd(1) is just a link to passwd(1), so NIS works with either command.
pw(8) is a command line utility to 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 here.