Name: Server control

Unix-Short-name: tty_ctrl

Purpose:
When running a server on linux without keyboard, mouse and monitor, it is
sometimes necessary to excute administrative commands, e.g. changing CD's,
rebooting or shuting down the system, start of the Backup etc.
tty_ctrl offer's the opportunity to execute 7 sommands on such a computer.
Success or Errors while execution of the commands will be displayed wia
status led's. Further it starts as a daemon process and all actions
performed are logged by the syslog process, e.g. in the /var/log/messages
file.
If you recommend to execute other command than the default onex, simply
create al link in /sbin/tty_ctrl/button1..7 to your command, and it will
be executed on the next startup of the program.

Preconditions:
You'll need a free serial line, three resistors, 7 buttons, three led's 6
diodes and of course a soldering pen to get this stuff together.
The hardware is available at any electronic market, and costs less than 5
DM (sorry, as i don't order anything in USA, i don't know the price in $,
if you have an idea, of the price in $, please mail to:
peter.pfrang@gmx.de).


How does it work?
tty_control monitors the status signals of the serial line. Recieve and
Transmit Data Signals are not not used for this purpose.
The Signals used are: Carrier Detect, Data Set Ready, Clear To Send and Ring Indicator
(4 signals, 3 are the combination of CD && DSR, CTS && CD, DSR && CTS
(Do not try to derive anything from RI && something, this won't work))
The power for driving the led's is derived from the serial line itself.
Depending on the signal whether the default command or the user defined
command is executed.
It is not possible to execute 2 commands at one time.

