Single key halt andor reboot
On Tue, 06 Dec 2005, in the Usenet newsgroup comp.os.linux.misc, in article
My firewall is similar (ex laptop of some kind long forgotten - a 386SX sans display, keyboard or case). It has two serial ports, one of which is connected (null modem cable) to one of the work stations for control. (See the Remote-Serial-Console-HOWTO for details.) The second port used to be used for a UPS (I no longer bother, as when power fails, I also loose the broadband, so what's the use). You could use the concept of a UPS shutdown via the serial port, with a toggle switch simulating the "Oh, Oh, better shut down now, cause the battery has about had it" signal. You ought to be able to figure out how from the UPS-HOWTO. Note that most switches had a little 'contact bounce', so on detecting the switch closure, sleep a second or two and then verify that the switch contact had been made.
So this is the setup: One computer, 2 ATA hard drives, one CD-DVD burner, no...
Should be possible, but I suspect it's more work than needed.
On comp.os.linux.misc, in Here's a very simple example, a function (which is like a script) that you put in your .bashrc...
Security problem, but there's nothing that requires root to log in. I suspect you could start a daemon out ofetc-inittab or the boot scripts and have it monitor a switch function (intentionally vague statement), and on detecting this (and perhaps waiting a second or two and verifying that the switch is still pressed), initiate a shutdown. A second switch could select -r or -h options, etc. Again, the UPS-HOWTO ought to give clues.
Old guy