4.4BSD/usr/share/man/cat5/passwd.5
PASSWD(5) BSD Programmer's Manual PASSWD(5)
NNAAMMEE
ppaasssswwdd - format of the password file
DDEESSCCRRIIPPTTIIOONN
The ppaasssswwdd files are files consisting of newline separated records, one
per user, containing ten colon (``:'') separated fields. These fields
are as follows:
name User's login name.
password User's _e_n_c_r_y_p_t_e_d password.
uid User's id.
gid User's login group id.
class User's general classification (unused).
change Password change time.
expire Account expiration time.
gecos General information about the user.
home_dir User's home directory.
shell User's login shell.
The _n_a_m_e field is the login used to access the computer account, and the
_u_i_d field is the number associated with it. They should both be unique
across the system (and often across a group of systems) since they con-
trol file access.
While it is possible to have multiple entries with identical login names
and/or identical user id's, it is usually a mistake to do so. Routines
that manipulate these files will often return only one of the multiple
entries, and that one by random selection.
The login name must never begin with a hyphen (``-''); also, it is
strongly suggested that neither upper-case characters or dots (``.'') be
part of the name, as this tends to confuse mailers. No field may contain
a colon (``:'') as this has been used historically to separate the fields
in the user database.
The password field is the _e_n_c_r_y_p_t_e_d form of the password. If the
_p_a_s_s_w_o_r_d field is empty, no password will be required to gain access to
the machine. This is almost invariably a mistake. Because these files
contain the encrypted user passwords, they should not be readable by any-
one without appropriate privileges.
The group field is the group that the user will be placed in upon login.
Since this system supports multiple groups (see groups(1)) this field
currently has little special meaning.
The _c_l_a_s_s field is currently unused. In the near future it will be a key
to a termcap(5) style database of user attributes.
The _c_h_a_n_g_e field is the number in seconds, GMT, from the epoch, until the
password for the account must be changed. This field may be left empty
to turn off the password aging feature.
The _e_x_p_i_r_e field is the number in seconds, GMT, from the epoch, until the
account expires. This field may be left empty to turn off the account
aging feature.
The _g_e_c_o_s field normally contains comma (``,'') separated subfields as
follows:
name user's full name
office user's office number
wphone user's work phone number
hphone user's home phone number
This information is used by the finger(1) program.
The user's home directory is the full UNIX path name where the user will
be placed on login.
The shell field is the command interpreter the user prefers. If there is
nothing in the _s_h_e_l_l field, the Bourne shell (_/_b_i_n_/_s_h) is assumed.
SSEEEE AALLSSOO
chpass(1), login(1), passwd(1), getpwent(3), adduser(8),
pwd_mkdb(8), vipw(8)
BBUUGGSS
User information should (and eventually will) be stored elsewhere.
CCOOMMPPAATTIIBBIILLIITTYY
The password file format has changed since 4.3BSD. The following awk
script can be used to convert your old-style password file into a new
style password file. The additional fields ``class'', ``change'' and
``expire'' are added, but are turned off by default. Class is currently
not implemented, but change and expire are; to set them, use the current
day in seconds from the epoch + whatever number of seconds of offset you
want.
BEGIN { FS = ":"}
{ print $1 ":" $2 ":" $3 ":" $4 "::0:0:" $5 ":" $6 ":" $7 }
HHIISSTTOORRYY
A ppaasssswwdd file format appeared in Version 6 AT&T UNIX.
4.4BSD June 5, 1993 2