Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

PASSWD(5)                     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 (":")
     separated 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
     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 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
     anyone 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
     defined in login.conf(5), which is a capfile(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.  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
     configurable period (defaulting to 14 days) before the event.

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

           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(1), 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
     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 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
     systems, the passwd field may also be overridden.

     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 }

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

     Managing NFS and NIS (O'Reilly & Associates)

     A passwd file format appeared in Version 1 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.

NetBSD 10.99                   September 1, 2019                  NetBSD 10.99