passwd(5) BSD File Formats Manual passwd(5)
NAME
passwd, master.passwd -- format of the password file
DESCRIPTION
The /etc/passwd file is a legacy BSD 4.3 format file. It is mostly
unused, but is updated by some utility programs. Its format is similar
to the /etc/master.passwd file, except that it does not contain the
class, change, and expire fields described below.
The /etc/master.passwd file comprises newline separated records, one per
user. Each line contains 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 User's full name.
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.
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 the user's full name. Note that Mac OS
X differs from some other operating systems, where the gecos field may
contain other comma-separcted information about the user.
The home_dir field is the user's home directory. This is the full 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.
INTERACTION WITH DIRECTORY SERVICES
Processes generally find user records using one of the getpwent(3) family
of functions. On Mac OS X, these functions interact with the
DirectoryService(8) daemon, which reads the /etc/master.passwd file as
well as searching other directory information services to find user
accounts.
FILES
/etc/passwd
/etc/master.passwd
SEE ALSO
chpass(1), login(1), passwd(1), getpwent(3), netgroup(5),
DirectoryService(8), pwd_mkdb(8), vipw(8)
HISTORY
A passwd file format appeared in Version 6 AT&T UNIX.
BSD July 18, 1995 BSD
Mac OS X 10.8 - Generated Sat Sep 1 14:15:02 CDT 2012