passwd.5yp

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)passwd.5yp	8.1	9/11/90
.TH passwd 5yp
.SH Name
passwd \- password file description with the Yellow Pages service implemented
.SH Description
.NXR "passwd file (YP)" "format"
The 
.PN passwd
file stores initial login information, including passwords
for each user in the system.
Regardless of whether or not the system has the Yellow Pages service
implemented, the
.PN passwd
file contains the
following information:
.HP 10
Name (login name, contains no uppercase)
.br
.ns
.HP 10
Encrypted password
.br
.ns
.HP 10
Numerical user ID
.br
.ns
.HP 10
Numerical group ID
.br
.ns
.HP 10
User's real name, office, extension, home phone.
.br
.ns
.HP 10
Initial working directory
.br
.ns
.HP 10
Program to use as Shell
.PP
The name can contain an ampersand (&), meaning insert the login name.
This information is set by the
.MS chfn 1
command and used by the
.MS finger 1
command.
.PP
This 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, the system defaults to the 
.PN /bin/sh
shell.
.PP
This file resides in the 
.PN /etc
directory.
Because of the encrypted
passwords, it can and does have general read
permission and can be used, for example,
to map numerical user IDs to names.
.PP
Appropriate precautions must be taken to lock the
.PN /etc/passwd
file against simultaneous changes if it is to
be edited with a text editor.
The
.PN vipw
command does the necessary locking.
.PP
In a Yellow Pages environment, the
.PN passwd
file can also have a line beginning with a plus (+),
which means to incorporate entries from the Yellow Pages data base.
There are three styles of + entries:
by itself, + means to insert the entire contents
of the Yellow Pages password file at that point;
.I +name
means to insert the entry (if any) for
.I name
from the Yellow Pages at that point;
.I +@name
means to insert the entries for all members of the network group
.I name
at that point.
If a + entry has a nonnull password, directory, gecos, or shell field,
it will override what is contained in the Yellow Pages.
The numerical user ID and group ID fields cannot be overridden.
.SH Examples
.PP
Here is a sample 
.PN /etc/passwd
file:
.EX
root:q.mJzTnu8icF.:0:10:Privileged Account:/:/bin/csh
jcj:6k/7KCFRPNVXg:508:10:JC Javert:/usr2/jcj:/bin/csh
+john:
+@documentation:no-login:
+:::Guest
.EE
.PP
In this example, there are specific entries for users
.I root
and
.I jcj,
in case the Yellow Pages are temporarily out of service.
Alternatively, a user may need specific login information on a given
system that differs from the information contained in the Yellow Pages
map for that user.
The user, john,
will have his password entry in the Yellow Pages
incorporated without change.
Anyone in the netgroup
.I documentation
will have their password field disabled,
and anyone else will be able to log in with their usual password,
shell, and home directory, but with a gecos field of
.I Guest.
.SH Files
.PN /etc/passwd
.SH See Also
chfn(1), finger(1), login(1), passwd(1), crypt(3),
getpwent(3), group(5), adduser(8), vipw(8)