Installation guide

Enabling Halt Key Functions (tta0_halts and tta1_halts)

Why Enable

Halt Key

Functions?

To invoke console mode (halt the system), you must press the

Halt button on the system. Alternatively, you can invoke console

mode from a terminal keyboard. You enable this ability by

setting an environment variable:

• tta0_halts allows you to invoke console mode from the

console terminal keyboard by pressing Ctrl/P or

Break

• tta1_halts allows you to invoke console mode from the

keyboard of a device connected to the auxiliary serial port by

pressing Ctrl/P.

Possible

Settings

Possible settings for each environment variable are as follows:

tta0_halts

Setting

tta1_halts

Setting Description

0 0 (default) Ctrl/P and

Break

are disabled.

2 2 Ctrl/P is enabled.

4 (default) –

Break

is enabled.

6 – Both Ctrl/P and

Break

are enabled.

Your System’s

Current Halt

Key Settings

Display the current halt key settings for the two different ports

as follows.

Displaying Your Console Terminal’s Halt Key Settings

To display your console terminal keyboard’s current halt key

settings, enter the following:

>>> show tta0_halts

Return

tta0_halts 4

In this example, tta0_halts is set to 4:

Break

is enabled.

4–18 Setting Environment Variables