Turning monitor off (manually or on timeout)

Latest response

I run either debian or newly installed rhel in server mode (multi-user.target). In both, the monitor keeps turning itself ON for no apparent reason. In deb I use a utility 'vbetool' to turn monitor off remotely, but the said tools is not available in rhel afaik.
Is there an alternative in rhel, or any of its power management system that I can use to achieve that goal?
TIA.

Responses

As far as I remember, vbetool will poke the registers of the display controller directly, bypassing kernel control. It would be better to tell the kernel what you want to happen, and let it handle the hardware. The advantage of this approach is that it will also work on systems with UEFI firmware, which might not have anything resembling the VESA BIOS extension expected by the vbetool command.

The default console blanking timeout is 10 minutes (600 seconds).

This command will make the screen go blank (and powered-off after a few seconds) and stay blanked even if someone uses the console keyboard:

# setterm --blank force --term linux </dev/tty1

To unblank:

# setterm --blank poke --term linux < /dev/tty1

If you enter these commands on the system console, you can omit the "--term linux < /dev/tty1" part. (Might be handy to know if you need to log on blindly and then unblank the display...)