Installation guide

9.1.1 The Password File
The passwd file for a standalone system identifies each user (including
root) on your system. Each passwd file entry is a single line that contains
seven fields. The fields are separated by colons and the last field ends with
a new-line character. The syntax of each entry and the meaning of each
field is as follows:
username:password:user_id:group_id:user_info:\
login_directory:login_shell
username
The name for the user account. The username
must be unique and consist of from one to eight
alphanumeric characters.
password
You cannot enter a password directly. Enter an
asterisk (*) in the passwd field to disable a login to
that account. An empty password field allows
anyone who knows the login name to log in to your
system as that user. Refer to Section 9.2.1.4 for
instructions on assigning a user password with the
passwd command.
user_id
The UID for this account. This is an integer with
the limit determined by the value of maximum
UIDs enabled on the system and must be unique for
each user on the system. Refer to Section 9.1.4 for
information on UID and GID values. Reserve the
UID 0 for root. Assign each UID in ascending order
beginning with 100. Lower numbers are used for
pseudousers such as bin or daemon.
group_id
The GID for this account. This is an integer between
0 and 32767. Reserve the GID 0 for the system
group. Be sure to define the GID in the group file.
user_info
This field contains additional user information such
as the full user name, office address, telephone
extension, and home phone. The finger command
reads the information in the
user_info field.
Users can change the contents of their
user_info
field with the passwd command. Refer to
Section 9.3.2, as well as the finger
(1) and
passwd
(1) reference pages for more information.
9–2 Administering User Accounts and Groups