SULOGIN(8)

NAME
sulogin - Single-user login

SYNTAX

sulogin [tty-device]

DESCRIPTION

The sulogin command is invoked by init prior to allowing the user access to the system when in single user mode. This feature may only be available on certain systems where init has been modified accordingly, or where the /etc/inittab has an entry for a single user login.

The user is prompted

Type control-d to proceed with normal startup, (or give root password for system maintenance):

Input and output will be performed with the standard file descriptors unless the optional device name argument is provided.

If the user enters the correct root password, a login session is initiated. When EOF is pressed instead, the system enters multi-user mode.

After the user exits the single-user shell, or presses EOF, the system begins the initialization process required to enter multi-user mode.

CAVEATS

This command can only be used if init has been modified to call sulogin instead of /bin/sh, or if the user has set the inittab to support a single user login. For example, the line:

co:s:respawn:/etc/sulogin /dev/console

should execute the sulogin command in single user mode.

As complete an environment as possible is created. However, various devices may be unmounted or uninitialized and many of the user commands may be unavailable or nonfunctional as a result.

CONFIGURATION

The following configuration variables in /etc/login.defs change the behavior of this tool:

ENV_HZ (string)
    If set, it will be used to define the HZ environment variable when a user login. The value must be preceded by HZ=. A common value on Linux is HZ=100.

ENV_TZ (string)
    If set, it will be used to define the TZ environment variable when a user login. The value can be the name of a timezone preceded by TZ= (for example TZ=CST6CDT), or the full path to the file containing the timezone specification (for example /etc/tzname).

    If a full path is specified but the file does not exist or cannot be read, the default is to use TZ=CST6CDT.

FILES

/etc/passwd
    User account information.

/etc/shadow
    Secure user account information.

SEE ALSO

login(1), sh(1), init(8).