'\" t
.\"     Title: login
.\"    Author: Julianne Frances Haugh
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 2024-02-04
.\"    Manual: 用户命令
.\"    Source: shadow-utils 4.13
.\"  Language: Chinese Simplified
.\"
.TH "LOGIN" "1" "2024-02-04" "shadow\-utils 4\&.13" "用户命令"
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.SH "名称"
login \- 在系统上启动回话
.SH "大纲"
.HP \w'\fBlogin\fR\ 'u
\fBlogin\fR [\-p] [\-h\ \fIhost\fR] [\fI用户名\fR] [\fIENV=VAR\fR...]
.HP \w'\fBlogin\fR\ 'u
\fBlogin\fR [\-p] [\-h\ \fIhost\fR] \-f \fI用户名\fR
.HP \w'\fBlogin\fR\ 'u
\fBlogin\fR [\-p] \-r\ \fIhost\fR
.SH "描述"
.PP
The
\fBlogin\fR
program is used to establish a new session with the system\&. It is normally invoked automatically by responding to the
\fIlogin:\fR
prompt on the user\*(Aqs terminal\&.
\fBlogin\fR
may be special to the shell and may not be invoked as a sub\-process\&. When called from a shell,
\fBlogin\fR
should be executed as
\fBexec login\fR
which will cause the user to exit from the current shell (and thus will prevent the new logged in user to return to the session of the caller)\&. Attempting to execute
\fBlogin\fR
from any shell but the login shell will produce an error message\&.
.PP
The user is then prompted for a password, where appropriate\&. Echoing is disabled to prevent revealing the password\&. Only a small number of password failures are permitted before
\fBlogin\fR
exits and the communications link is severed\&.
.PP
If password aging has been enabled for your account, you may be prompted for a new password before proceeding\&. You will be forced to provide your old password and the new password before continuing\&. Please refer to
\fBpasswd\fR(1)
for more information\&.
.PP
Your user and group ID will be set according to their values in the
/etc/passwd
file\&. The value for
\fB$HOME\fR,
\fB$SHELL\fR,
\fB$PATH\fR,
\fB$LOGNAME\fR, and
\fB$MAIL\fR
are set according to the appropriate fields in the password entry\&. Ulimit, umask and nice values may also be set according to entries in the GECOS field\&.
.PP
On some installations, the environmental variable
\fB$TERM\fR
will be initialized to the terminal type on your tty line, as specified in
/etc/ttytype\&.
.PP
命令解释器的初始化脚本也可能执行。请参考手册中相应的章节来获取关于此功能的更多信息。
.PP
在登录 shell 中以第一个字符是\(lq*\(rq标注的是子系统登录。给定的主目录将被用于用户实际登录的新文件系统的根。
.PP
The
\fBlogin\fR
program is NOT responsible for removing users from the utmp file\&. It is the responsibility of
\fBgetty\fR(8)
and
\fBinit\fR(8)
to clean up apparent ownership of a terminal session\&. If you use
\fBlogin\fR
from the shell prompt without
\fBexec\fR, the user you use will continue to appear to be logged in even after you log out of the "subsession"\&.
.SH "选项"
.PP
\fB\-f\fR
.RS 4
不要执行认证，用户已经预认证过。
.sp
Note: In that case,
\fIusername\fR
is mandatory\&.
.RE
.PP
\fB\-h\fR
.RS 4
此登录的远程主机名。
.RE
.PP
\fB\-p\fR
.RS 4
保留环境。
.RE
.PP
\fB\-r\fR
.RS 4
为 rlogin (远程登录)执行 autologin (自动登录)协议。
.RE
.PP
The
\fB\-r\fR,
\fB\-h\fR
and
\fB\-f\fR
options are only used when
\fBlogin\fR
is invoked by root\&.
.SH "CAVEATS"
.PP
This version of
\fBlogin\fR
has many compilation options, only some of which may be in use at any particular site\&.
.PP
文件的位置由系统配置决定。
.PP
The
\fBlogin\fR
program is NOT responsible for removing users from the utmp file\&. It is the responsibility of
\fBgetty\fR(8)
and
\fBinit\fR(8)
to clean up apparent ownership of a terminal session\&. If you use
\fBlogin\fR
from the shell prompt without
\fBexec\fR, the user you use will continue to appear to be logged in even after you log out of the "subsession"\&.
.PP
As with any program,
\fBlogin\fR\*(Aqs appearance can be faked\&. If non\-trusted users have physical access to a machine, an attacker could use this to obtain the password of the next person coming to sit in front of the machine\&. Under Linux, the SAK mechanism can be used by users to initiate a trusted path and prevent this kind of attack\&.
.SH "配置文件"
.PP
The following configuration variables in
/etc/login\&.defs
change the behavior of this tool:
.SH "文件"
.PP
/var/run/utmp
.RS 4
当前登录会话的列表。
.RE
.PP
/var/log/wtmp
.RS 4
先前的登录会话列表。
.RE
.PP
/etc/passwd
.RS 4
用户账户信息。
.RE
.PP
/etc/shadow
.RS 4
安全用户账户信息。
.RE
.PP
/etc/motd
.RS 4
System message of the day file\&.
.RE
.PP
/etc/nologin
.RS 4
阻止非 root 用户登录。
.RE
.PP
/etc/ttytype
.RS 4
终端类型列表。
.RE
.PP
$HOME/\&.hushlogin
.RS 4
阻止显示系统信息。
.RE
.PP
/etc/login\&.defs
.RS 4
Shadow 密码套件配置。
.RE
.SH "参见"
.PP
\fBmail\fR(1),
\fBpasswd\fR(1),
\fBsh\fR(1),
\fBsu\fR(1),
\fBlogin.defs\fR(5),
\fBnologin\fR(5),
\fBpasswd\fR(5),
\fBsecuretty\fR(5),
\fBgetty\fR(8)\&.