PASSWD(5) BSD File Formats Manual PASSWD(5)NAMEpasswd — format of the password file
DESCRIPTION
The passwd 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 encrypted 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 name field is the login used to access the computer account, and the
uid 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 encrypted form of the password. If the
password 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 class field is currently unused. In the near future it will be a key
to a termcap(5) style database of user attributes.
The change 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 expire 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 gecos 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 shell field, the Bourne shell (/bin/sh) is assumed.
SEE ALSOchpass(1), login(1), passwd(1), getpwent(3), adduser(8), pwd_mkdb(8),
vipw(8)BUGS
User information should (and eventually will) be stored elsewhere.
COMPATIBILITY
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 }
HISTORY
A passwd file format appeared in Version 6 AT&T UNIX.
BSD June 5, 1993 BSD
