The kbd utility manipulates the state of the keyboard, or displays the keyboard type, or allows the default keyboard abort sequence effect to be changed. The abort sequence also applies to serial console devices. The kbd utility sets the /dev/kbd default keyboard device.

The -i option reads and processes default values for the keyclick and keyboard abort settings from the /etc/default/kbd keyboard default file. Only keyboards that support a clicker respond to the -c option. To turn clicking on by default, add or change the value of the KEYCLICK variable in the /etc/default/kbd file to:

KEYCLICK=on

Next, run the command kbd -i to change the setting. Valid settings for the KEYCLICK variable are on and off; all other values are ignored. If the KEYCLICK variable is not specified in the default file, the setting is unchanged.

The keyboard abort sequence effect (L1-A or STOP-A on the keyboard, and BREAK on the serial console input device on most systems) can only be changed by a superuser using the -a option. The system can be configured to ignore the keyboard abort sequence or trigger on the standard or alternate sequence.

A BREAK condition that originates from an erroneous electrical signal cannot be distinguished from one deliberately sent by remote DCE. As a remedy, use the -a option with Alternate Break to switch break interpretation. Due to the risk of incorrect sequence interpretation, binary protocols such as PPP, SLIP, and others should not be run over the serial console port when Alternate Break sequence is in effect. The Alternate Break sequence has no effect on the keyboard abort. For more information on the Alternate Break sequence, se zs(7D) ,se(7D), and asy(7D).

On many systems, the default effect of the keyboard abort sequence is to suspend the operating system and enter the debugger or the monitor. Some systems feature key switches with a secure position. On these systems, setting the key switch to the secure position overrides any software default set with this command.

To permanently change the software default effect of the keyboard abort sequence, first add or change the value of the KEYBOARD_ABORT variable in the /etc/default/kbd file to:

KEYBOARD_ABORT=disable

Next, run the command kbd -i to change the setting. Valid settings are enable, disable, and alternate; all other values are ignored. If the variable is not specified in the default file, the setting is unchanged.

To set the abort sequence to the hardware BREAK, set the value of the KEYBOARD_ABORT variable in the /etc/default/kbd file to:

 KEYBOARD_ABORT=enable

To change the current setting, run the command kbd -i. To set the abort sequence to the Alternate Break character sequence, first set the current value of the KEYBOARD_ABORT variable in the /etc/default/kbd file to:

 KEYBOARD_ABORT=alternate

Next, run the command kbd -i to change the setting. When the Alternate Break sequence is in effect, only serial console devices are affected.

The kbd utility supports the following options:

-i

Set keyboard defaults from the keyboard default file. With the exception of -d keyboard device, this option cannot be used with any other option. The -i option instructs the keyboard command to read and process keyclick and keyboard abort default values from the /etc/default/kbd file. The -i option can only be used by a superuser.

-r

Reset the keyboard as if power-up

-t

Return the type of the keyboard being used

-c on/off state

Turn the clicking of the keyboard on or off.

on

Enable clicking

off

Disable clicking

-a enable/disable/alternate state

Enable, disable, or alternate the keyboard abort sequence effect. By default, a keyboard abort sequence (typically Stop-A or L1-A on the keyboard and BREAK on the serial console device) suspends the operating system on most systems. The default keyboard behavior can be changed using this option. The -a option can only be used by a superuser.

enable

Enable the default effect of the keyboard abort sequence (suspend the operating system and enter the debugger or the monitor)

disable

Disable the default/alternate effect and ignore keyboard abort sequences

alternate

Enable the alternate effect of the keyboard abort sequences (suspend the operating system and enter the debugger or the monitor) upon receiving the Alternate Break character sequence on the console. The Alternate Break sequence is defined by the drivers zs(7D), se(7D), asy(7D). Due to a risk of incorrect sequence interpretation, binary protocols cannot be run over the serial console port when this value is used.

-d keyboard device

Specify the keyboard device being set. The default setting is /dev/kbd.

/etc/rcS

shell script containing commands necessary to get the system to single-user mode

/dev/kbd

keyboard device file

/etc/default/kbd

keyboard default file containing software defaults for keyboard configurations.

See attributes(5) for descriptions of the following attributes:

loadkeys(1), kadb(1M), keytables(4), attributes(5), kb(7M), zs(7D), se(7D), asy(7D)

Some server systems have key switches with a secure key position that can be read by system software. This key position overrides the normal default of the keyboard abort sequence effect and changes the default so the effect is disabled. When the key switch is in the secure position on these systems, the keyboard abort sequence effect cannot be overridden by the software default, which is settable with the kbd utility.

Currently, there is no way to determine the state of the keyboard click setting.