passwd(4) DG/UX 4.30 passwd(4)
NAME
passwd - password file
SYNOPSIS
/etc/passwd
DESCRIPTION
The passwd file contains for each user the following
information:
name User's login name. Contains no uppercase
characters and must not be greater than USR_NAME
(see limits(4)) characters long.
password encrypted password.
numerical user id
This is the user's id in the system and it must be
unique. Otherwise, users with the same uid will
be able to access each other's files.
numerical group id
This is the number of the group that the user
belongs to.
user's real name
Some system administrators use this field to
contain the user's office, extension, home phone,
and so on. For historical reasons this field is
called the GCOS field.
initial working directory
The directory that the user is positioned in when
they log in - this is also known as the home
directory.
shell program to use as shell when the user logs in.
The user's real name field may contain `&', meaning to
insert the login name.
The password file is an ASCII file. Each field within each
user's entry is separated from the next by a colon. Each
user is separated from the next by a new-line. If the
password field is null, no password is demanded; if the
shell field is null, /bin/sh is used.
This file resides in directory /etc. Because of the
encrypted passwords, it has general read permission. It can
be used, for example to map numerical user IDs to names.
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passwd(4) DG/UX 4.30 passwd(4)
The encrypted password consists of 13 characters chosen from
a 64-character alphabet ( . , / , 0-9 , A-Z , a-z ), except
when the password is null. In that case, the encrypted
password is also null. Password aging is affected for a
particular user if the user's encrypted password in the
password file is followed by a comma and a non-null string
of characters from the above alphabet (such a string must
first be introduced by the superuser).
The first character of the age denotes the maximum number of
weeks for which a password is valid. If you try to login
after your password has expired, you must supply a new one.
The next character denotes the minimum period in weeks that
must elapse before the password may be changed. The
remaining characters define the week (counted from the
beginning of 1970) when the password was last changed ( a
null string is equivalent to zero). The first and second
characters have numerical values in the range 0-63 that
correspond to the 64-character alphabet shown above (i.e., /
= 1 week; z = 63 weeks). If both characters are equal to
zero (derived from the string "." or ".."), you must change
your password the next time you login. The age will
disappear from your entry in the password file. If the
second character is greater than the first (signified, e.g.,
by the string "./"), then only the superuser will be able to
change the password.
The passwd file can also have lines beginning with a plus
(+), which means to incorporate entries from the Yellow
Pages.
NOTE:
You must be using the DG/UX Open Network
Computing/Network File System (ONC/NFS) to use this
feature. If you use DG/UX ONC/NFS, see passwd(5).
There are three styles of + entries: all by itself, + means
to insert the entire contents of the Yellow Pages password
file at that point; +name means to insert the entry (if any)
for name from the Yellow Pages at that point; +@name means
to insert the entries for all members of the network group
name at that point. If a + entry has a non-null password,
directory, user's real name, or shell field, they will
override what is contained in the Yellow Pages. The
numerical user ID and group ID fields cannot be overridden.
Entries beginning with a minus sign (-) are also allowed.
They have two formats: -name and -@name. The meaning of
these formats is the same as for +name and +@name,
respectively, except that the action is reversed; all
members matched are considered to be excluded from the
password file, regardless of subsequent entries. Minus
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passwd(4) DG/UX 4.30 passwd(4)
entries can be used to exclude specific entries from the
Yellow Pages.
EXAMPLE
Here is a sample /etc/passwd file:
root:q.mJzTnu8icF.:0:10:God:/:/bin/csh
tut:6k/7KCFRPNVXg:508:10:Bill Tuthill:/usr/tut:/bin/csh
+john:
-@documentation:no-login:
+:::Guest
john::605:20:John Smith:/usr/john:
In this example, there are specific entries for users root
and tut, in case the Yellow Pages are not running. (See
Managing NFS and Its Facilities on the DG/UXTM System.) The
user john will have his password entry in the Yellow Pages
incorporated without change; anyone in the netgroup
documentation will have their password field disabled, and
anyone else will be able to login with their usual password,
shell, and home directory, but with a GCOS field of Guest.
The second entry for john in this example will not be used
if the Yellow Pages are running; the first entry for a given
user name will be used if multiple entries exist.
Appropriate precautions must be taken to lock the
/etc/passwd file against simultaneous changes if it is to be
edited with a text editor; vipw(1M) does the necessary
locking. The password file can be scanned for
inconsistencies using pwck(1M).
FILES
/etc/passwd
SEE ALSO
getpwent(3C), login(1), crypt(3C), passwd(1), passwd(5),
group(4), vipw(1M), adduser(8), pwck(1M), limits(4)
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