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PASSWD(5)		    BSD	File Formats Manual		     PASSWD(5)

     passwd, master.passwd -- format of	the password file

     The passwd	files are the local source of password information.  They can
     be	used in	conjunction with the Hesiod domain `passwd' and	the NIS	maps
     `passwd.byname', `passwd.byuid', `master.passwd.byname', and
     `master.passwd.byuid', as controlled by nsswitch.conf(5).

     The master.passwd file is readable	only by	root, and consists of newline
     separated ASCII records, one per user, containing ten colon (":") sepa-
     rated fields.

     Each line has the form:

     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.

     Be	aware that each	line is	limited	to 1024	characters; longer ones	will
     be	ignored.  This limit can be queried through sysconf(3) by using	the
     _SC_GETPW_R_SIZE_MAX parameter.

     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 "*".

     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 nor 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.  For the possible ciphers used	in
     this field	see passwd.conf(5).

     The gid 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 de-
     fined in login.conf(5), which is a	termcap(5) style database of user at-
     tributes, 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.  If this is set to	"-1" then the
     user will be prompted to change their password at the next	login.

     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.

     If	either of the change or	expire fields are set, the system will remind
     the user of the impending change or expiry	if they	login within a config-
     urable period (defaulting to 14 days) before the event.

     The gecos field normally contains comma (",") separated subfields as fol-

	   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 an 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 finger(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.

     If	`dns' is specified for the `passwd' database in	nsswitch.conf(5), then
     passwd lookups occur from the `passwd' Hesiod domain.

     If	`nis' is specified for the `passwd' database in	nsswitch.conf(5), then
     passwd lookups occur from the `passwd.byname', `passwd.byuid',
     `master.passwd.byname', and `master.passwd.byuid' NIS maps.

     If	`compat' is specified for the `passwd' database, and either `dns' or
     `nis' is specified	for the	`passwd_compat'	database in nsswitch.conf(5),
     then the passwd file also supports	standard `+/-' exclusions and inclu-
     sions, based on user names	and netgroups.

     Lines beginning with a minus sign ("-") are entries marked	as being ex-
     cluded from any following inclusions, which are marked with a plus	sign

     If	the second character of	the line is an 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 remainder 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	`passwd_compat:	dns') or
     `passwd.byname' and `passwd.byuid'	NIS maps (with `passwd_compat: nis')
     to	be included.

     If	the entry contains non-empty uid or gid	fields,	the specified numbers
     will override the information retrieved from the Hesiod domain or the NIS
     maps.  As well, if	the gecos, home_dir or shell entries contain text, it
     will override the information included via	Hesiod or NIS.	On some	sys-
     tems, the passwd field may	also be	overridden.

     chpass(1),	login(1), newgrp(1), passwd(1),	pwhash(1), getpwent(3),
     login_getclass(3),	login.conf(5), netgroup(5), passwd.conf(5),
     adduser(8), pwd_mkdb(8), vipw(8), yp(8)

     Managing NFS and NIS (O'Reilly & Associates)

     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.	 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 }

     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 NetBSD 1.4.

     The login.conf(5) capability first	appeared in NetBSD 1.5.

     User information should (and eventually will) be stored elsewhere.

     Placing `compat' exclusions in the	file after any inclusions will have
     unexpected	results.

BSD				 June 21, 2007				   BSD


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