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From: @(#)passwd.5 8.1 (Berkeley) 6/5/93
$Id$
.Dd September 29, 1994 .Dt PASSWD 5 .Os .Sh NAME .Nm passwd .Nd format of the password file .Sh DESCRIPTION The .Nm passwd files are files consisting of newline separated records, one per user, containing ten colon (``:'') separated fields. These fields are as follows:
p l -tag -width password -offset indent t name User's login name. t password User's .Em encrypted password. t uid User's id. t gid User's login group id. t class User's general classification (unused). t change Password change time. t expire Account expiration time. t gecos General information about the user. t home_dir User's home directory. t shell User's login shell. .El
p The .Ar name field is the login used to access the computer account, and the .Ar 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.
p 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.
p 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.
p The password field is the .Em encrypted form of the password. If the .Ar 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.
p The group field is the group that the user will be placed in upon login. Since this system supports multiple groups (see .Xr groups 1 ) this field currently has little special meaning.
p The .Ar class field is currently unused. In the near future it will be a key to a .Xr termcap 5 style database of user attributes.
p The .Ar change field is the number in seconds, .Dv 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.
p The .Ar expire field is the number in seconds, .Dv GMT , from the epoch, until the account expires. This field may be left empty to turn off the account aging feature.
p The .Ar gecos field normally contains comma (``,'') separated subfields as follows:
p d -unfilled -offset indent name user's full name office user's office number wphone user's work phone number hphone user's home phone number .Ed
p This information is used by the .Xr finger 1 program.
p The user's home directory is the full .Tn UNIX path name where the user will be placed on login.
p The shell field is the command interpreter the user prefers. If there is nothing in the .Ar shell field, the Bourne shell
q Pa /bin/sh is assumed. .Sh YP/NIS INTERACTION The
a /etc/passwd file can be configured to enable the YP/NIS group database. An entry whose .Ar name field consists of a plus sign (`+') followed by a login name, will be replaced internally to the C library with the YP/NIS password entry for the named group. An entry whose .Ar name field consists of a single plus sign with no login name following, will be replaced with the entire YP/NIS .Dq Li passwd.byname map.
p If any fields other than the login name are left empty, they will be used to override the YP/NIS database's values. So, for example, an
a /etc/master.passwd entry of: d -literal -offset indent +:::::::::/etc/noaccess .Ed would use the entire contents of the YP/NIS password database, but each entry would have its designated shell replaced by
a /etc/noaccess (presumably, a program to tell those users that they are not allowed to access the machine). This is the only way to specify values for the fields which are not present in the Sixth Edition format used by YP/NIS.
p If the YP/NIS password database is enabled for any reason, all reverse lookups (i.e., .Fn getpwuid ) will use the entire database, even if only a few logins are enabled. Thus, the login name returned by .Fn getpwuid is not guaranteed to have a valid forward mapping. .Sh FILES l -tag -width /etc/master.passwd -compact t Pa /etc/passwd ASCII password file, with passwords removed t Pa /etc/pwd.db .Xr db 3 -format password database, with passwords removed t Pa /etc/master.passwd ASCII password file, with passwords intact t Pa /etc/spwd.db .Xr db 3 -format password database, with passwords intact .El .Sh SEE ALSO .Xr adduser 8 , .Xr chpass 1 , .Xr getpwent 3 , .Xr login 1 , .Xr passwd 1 , .Xr pwd_mkdb 8 , .Xr vipw 8 , .Xr yp 4 .Sh BUGS User information should (and eventually will) be stored elsewhere.
p The YP/NIS password database makes encrypted passwords visible to ordinary users, thus making password cracking easier.
p The YP/NIS password database is in old-style (Sixth Edition) format, and so cannot specify site-wide values for user login class, password expiration date, and other fields present in the current format and not in the old. .Sh 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 .Dq class , .Dq change and .Dq 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. d -literal -offset indent BEGIN { FS = ":"} { print $1 ":" $2 ":" $3 ":" $4 "::0:0:" $5 ":" $6 ":" $7 } .Ed .Sh HISTORY A .Nm file format appeared in .At v6 . The YP/NIS functionality is modeled after .Tn SunOS and first appeared in .Tn FreeBSD 1.1. The override capability is new in .Tn FreeBSD 2.0.