passwd(5)

NAME

passwd, master.passwd - format of the password file

DESCRIPTION

The passwd files are the local source of password informa

tion. They can
be used in conjunction with the Hesiod domains `passwd' and

`uid', and
the NIS maps `passwd.byname', `passwd.byuid', `master.pass

wd.byname', and
`master.passwd.byuid', as controlled by nsswitch.conf(5).

For consistency, none of these files should ever be modified

manually.

The master.passwd file is readable only by root, and con

sists 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 login class.

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 passwd file is generated from the master.passwd file by

pwd_mkdb(8),
has the class, change, and expire fields removed, and the

password field
replaced by a `*' character. In the master.passwd file, a

password of
`*' is used to indicate that no one can ever log into that

account using
password authentication (logins through other forms of au

thentication,
i.e. using ssh(1) keys, will still work). The field only

contains
encrypted passwords, and `*' can never be the result of en

crypting a
password.

The name field is the login used to access the computer ac

count, 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 control 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 sepa

rate the fields
in the user database.

The password field is the encrypted form of the password,

see crypt(3).
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 anyone 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 a key for a user's login class. Login

classes are
defined in login.conf(5), which is a termcap(5) style

database of user
attributes, accounting, resource, and environment settings.

The change field is the number of seconds from the epoch,

UTC, 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 of seconds from the epoch,

UTC, 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

The full name may contain a ampersand (``&'') which will be

replaced by
the capitalized login name when the gecos field is displayed

or used by
various programs such as finger(1), sendmail(8), etc.

The office and phone number subfields are used by the fin

ger(1) program,
and possibly other applications.

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.

HESIOD SUPPORT

If `dns' is specified for the `passwd' database in nss

witch.conf(5), then
passwd lookups occur from the `passwd' Hesiod domain.

NIS SUPPORT

If `nis' is specified for the `passwd' database in nss

witch.conf(5), then
passwd lookups occur from the `passwd.byname', `pass

wd.byuid',
`master.passwd.byname', and `master.passwd.byuid' NIS maps.

COMPAT SUPPORT

If `compat' is specified for the `passwd' database, and ei

ther `dns' or
`nis' is specified for the `passwd_compat' database in nss

witch.conf(5),
then the passwd file also supports standard `+/-' exclusions

and inclusions, based on user names and netgroups.

Lines beginning with a ``-'' (minus sign) are entries marked

as being
excluded from any following inclusions, which are marked

with a ``+''
(plus sign).

If the second character of the line is a ``@'' (at sign),

the operation
involves the user fields of all entries in the netgroup

specified by the
remaining characters of the name field. Otherwise, the re

mainder of the
name field is assumed to be a specific user name.

The ``+'' token may also be alone in the name field, which

causes all
users from either the Hesiod domain passwd (with `pass

wd_compat: dns') or
`passwd.byname' and `passwd.byuid' NIS maps (with `pass

wd_compat: nis')
to be included.

If the entry contains non-empty uid or gid fields, the spec

ified numbers
will override the information retrieved from the Hesiod do

main or the NIS
maps. As well, if the gecos, dir or shell entries contain

text, it will
override the information included via Hesiod or NIS. On

some systems,
the passwd field may also be overridden.

FILES

/etc/passwd ASCII password file, with passwords

removed
/etc/pwd.db db(3)-format password database, with

passwords

removed

/etc/master.passwd ASCII password file, with passwords

intact
/etc/spwd.db db(3)-format password database, with

passwords

intact

COMPATIBILITY

The password file format has changed since 4.3BSD. The fol

lowing 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 }

SEE ALSO

chpass(1), login(1), passwd(1), crypt(3), getpwent(3), lo

gin.conf(5),
netgroup(5), adduser(8), pw(8), pwd_mkdb(8), vipw(8), yp(8)

Managing NFS and NIS (O'Reilly & Associates)

HISTORY

A passwd file format appeared in Version 6 AT&T UNIX.

The NIS passwd file format first appeared in SunOS.

The Hesiod support first appeared in FreeBSD 4.1. It was

imported from
the NetBSD Project, where it first appeared in NetBSD 1.4.

BUGS

User information should (and eventually will) be stored

elsewhere.

Placing `compat' exclusions in the file after any inclusions

will have
unexpected results.

BSD February 8, 2005

BSD