shutdown Command

Purpose

Provides the capability to halt, power off, restart, or schedule a system shutdown or restart.

Syntax

shutdown [ -c ] [ -h ] [ --help ] [ -H ] [ -k ] [ --no-wall ] [ -P ] [ -r ] [ --show ] [ time ] [ wall...]

Description

The shutdown command halts, powers off, restarts, or schedules a system shutdown or restart. When the shutdown command is used without any flags, it performs the power off operation by default.

Flags

Table 1. Flags
Items	Description
-c	Cancels a shutdown. This option works only when a timed shutdown is scheduled with the `time` parameter. The `time` parameter value must not be now or +0.
-h	Powers off the system. However, the -h option does not override an explicit --halt flag. This option is equivalent to the -P option.
--help	Displays help about the shutdown command.
-H or --halt	Halts the system.
-k	Send the message specified by the `wall` parameter to all the users without halting, powering off or restarting the system.
--no-wall	Suppress the message specified by the `wall` parameter before the system is shut down.
-P or --poweroff	Powers off the system.
-r or --reboot	Restarts off the system.
--show	Displays any scheduled shutdown operation and the scheduled time of the operation.

Parameters

Table 2. Parameters
Item	Description
`time`	Specifies the time for a scheduled halt, power off, restart, or shutdown operation. The `time` parameter is optional. If the `time` parameter is not specified, the shutdown command waits for one minute (`+1`) before it performs the action. The following options are the valid values for the `time` parameter: `+m`- Specifies the time in mins. The shutdown command waits for `m` minutes before it performs the action. `now`- Takes immediate action. This option is equivalent to `+0`. `hh:mm`- Specifies an absolute time in 24-hour format. If the `time` parameter is used, the shutdown command broadcasts a warning message to all the logged-in users. The `wall` parameter is used to specify the warning message. The shutdown command also blocks all the non-root user logins five minutes before the scheduled time for shutdown of the system. These actions are performed only when the `time` parameter is used without the `now` or `+0` value.
`wall`	Specifies an optional wall message. This message is sent to all the logged-in users in addition to the standard shutdown warning before the shutdown operation is performed.

Exit status

This command returns the following exit values:

Table 3. Exit status
Item	Description
0	Successful completion.
Nonzero	A nonzero failure code is returned when the shutdown command fails.