passwd.5

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)passwd.5	8.1	9/11/90
.TH passwd 5 
.SH Name
passwd \- password file
.SH Description
.NXR "passwd file (general)" "format"
.NXAM "passwd command" "passwd file (general)"
The
.PN passwd
file is an ASCII file that contains the following information
for each user:
.sp
.RS
Login name
.br
Password field
.br
User ID
.br
Group ID
.br
User's real name, office, extension, home phone
.br
Initial working directory
.br
Program to use as Shell
.RE
.PP
Each line in the
.PN passwd
file represents a user entry.
Each field within a user entry
is separated from the next by a colon.
Each user entry 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, then 
.PN /bin/sh
is used.
.PP
This file resides in directory 
.PN /etc .
Because the password, if present, is encrypted, the
.PN passwd
file has general read
permission and can be used, for example,
to map user IDs to names.
.PP
The ``user's real 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
Appropriate precautions must be taken to lock the file against changes
if it is to be edited with a text editor.
The
.PN vipw
command does the necessary locking.
.PP
If the system is running UPGRADE security level and an asterisk appears 
in the password field, or if the system is running ENHANCED level, then the 
content of the password field is ignored and the password for the account
is located in the authentication database. See
.MS auth 5
and the
.I "Security Guide for Administrators"
for more information.
.PP
The files 
.PN /etc/passwd.dir 
and 
.PN /etc/passwd.pag , 
if they exist, contain
the hashed version of the 
.PN /etc/passwd 
file.  If present, they are used by the 
.PN getpwnam
and 
.PN getpwuid 
functions to retrieve entries rapidly.  See 
.MS mkpasswd 8 
for more information.
.PP
The 
.PN passwd
database can be distributed in a network by a naming service, 
such as Yellow Pages or BIND/Hesiod.  See the
.I Guide to the Yellow Pages Service
or the 
.I Guide to the BIND/Hesiod Service
for setup information.
.SH Restrictions
The ``name'' can contain only lowercase ASCII characters a to z and the 
numbers 0 to 9.
.SH Files
.PN /etc/passwd
.br
.PN /etc/passwd.dir 
.br
.PN /etc/passwd.pag
.SH See Also
chfn(1), finger(1), login(1), passwd(1), crypt(3), getpwent(3),
auth(5), group(5), adduser(8), mkpasswd(8), vipw(8) 
.br
.I "Guide to the BIND/Hesiod Service"
.br
.I "Guide to the Yellow Pages Service"
.br
.I "Security Guide for Administrators"