| LOGIN(1) | 用户命令 | LOGIN(1) |
login - 在系统上启动回话
login [-p] [-h host] [用户名] [ENV=VAR...]
login [-p] [-h host] -f 用户名
login [-p] -r host
The login program is used to establish a new session with the system. It is normally invoked automatically by responding to the login: prompt on the user's terminal. login may be special to the shell and may not be invoked as a sub-process. When called from a shell, login should be executed as exec login 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 login from any shell but the login shell will produce an error message.
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 login exits and the communications link is severed.
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 passwd(1) for more information.
Your user and group ID will be set according to their values in the /etc/passwd file. The value for $HOME, $SHELL, $PATH, $LOGNAME, and $MAIL 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.
On some installations, the environmental variable $TERM will be initialized to the terminal type on your tty line, as specified in /etc/ttytype.
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。
在登录 shell 中以第一个字符是“*”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。
The login program is NOT responsible for removing users from the utmp file. It is the responsibility of getty(8) and init(8) to clean up apparent ownership of a terminal session. If you use login from the shell prompt without exec, the user you use will continue to appear to be logged in even after you log out of the "subsession".
-f
Note: In that case, username is mandatory.
-h
-p
-r
The -r, -h and -f options are only used when login is invoked by root.
This version of login has many compilation options, only some of which may be in use at any particular site.
文件的位置由系统配置决定。
The login program is NOT responsible for removing users from the utmp file. It is the responsibility of getty(8) and init(8) to clean up apparent ownership of a terminal session. If you use login from the shell prompt without exec, the user you use will continue to appear to be logged in even after you log out of the "subsession".
As with any program, login's 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.
The following configuration variables in /etc/login.defs change the behavior of this tool:
CONSOLE_GROUPS (string)
Use with caution - it is possible for users to gain permanent access to these groups, even when not logged in on the console.
DEFAULT_HOME (boolean)
If set to yes, the user will login in the root (/) directory if it is not possible to cd to her home directory.
ENV_PATH (string)
ENV_SUPATH (string)
ERASECHAR (number)
此值可以使用前缀“0”表示八进制，“0x”表示十六进制。
FAIL_DELAY (number)
FAKE_SHELL (string)
HUSHLOGIN_FILE (string)
KILLCHAR (number)
此值可以使用前缀“0”表示八进制，“0x”表示十六进制。
LOGIN_RETRIES (number)
This will most likely be overridden by PAM, since the default pam_unix module has its own built in of 3 retries. However, this is a safe fallback in case you are using an authentication module that does not enforce PAM_MAXTRIES.
LOGIN_TIMEOUT (number)
LOG_OK_LOGINS (boolean)
LOG_UNKFAIL_ENAB (boolean)
注意：如果用户不小心将密码输入到了登录名中，记录未知用户名可能是一个安全隐患。
TTYGROUP (string), TTYPERM (string)
By default, the ownership of the terminal is set to the user's primary group and the permissions are set to 0600.
TTYGROUP can be either the name of a group or a numeric group identifier.
If you have a write program which is "setgid" to a special group which owns the terminals, define TTYGROUP to the group number and TTYPERM to 0620. Otherwise leave TTYGROUP commented out and assign TTYPERM to either 622 or 600.
TTYTYPE_FILE (string)
USERGROUPS_ENAB (boolean)
/var/run/utmp
/var/log/wtmp
/etc/passwd
/etc/shadow
/etc/motd
/etc/nologin
/etc/ttytype
$HOME/.hushlogin
/etc/login.defs
mail(1), passwd(1), sh(1), su(1), login.defs(5), nologin(5), passwd(5), securetty(5), getty(8).
| 2020-02-07 | shadow-utils 4.8.1 |