rshdown(1) - Linux man page

Name

rshdown - Remote shutdown.

Synopsis

rshdown [<configfile>]

Description

The program listens on an UDP port for shutdown data packets. If a valid shutdown data packet was received the program shuts down the computer.

If you have two computers powered by the same UPS you can connect the signal cable to one of them. If power is off for too long and the computer with the signal cable goes down it can notify the other computer to shut down too.

Return Value

The program is running as a daemon, it does not return a value.

Example

Create a file containing up to 1500 bytes random data (you can use the rndbytes program to do so).

Copy this file to /etc/rshdown-secret on both computers. Use a secure mechanism to transfer the file (i.e. scp) and set permissions to 600.

Choose a free port number on the shutdown master (the computer with the signal cable) and the shutdown slave (the other computer). In the example we use port 2 on both systems.

On the shutdown master modify the startup scripts to create an indicator file, i.e. ''/var/run/rshdown/rshdown.txt' on each reboot.

Modify the the shutdown scripts to check for the presence of the indicator file, if the file exists send the data packet.

#! /bin/sh
if [ -f /var/run/rshdown/rshdown.txt ]
then
  for i in 1 2 3 4 5 6 7 8 9 10
  do
    nc -u -p 2 -w 2 slave 2 < /etc/rshdown-secret
  done
fi

On the shutdown slave create a shutdown script /etc/powerfail-fast:

/etc/powerfail-full > /dev/null 2>&1 &

The /etc/powerfail-fast must return immediately, longer processes (the full shutdown) must go to background.

The /etc/powerfail-full script, i.e.

/usr/sbin/poweroff

does a shutdown of the system.

Create the configuration file /etc/rshdown.conf

sender-ip     192.168.1.2
sender-port   2
receiver-ip   192.168.1.3
receiver-port 2
file          /etc/rshdown-secret
action        /etc/powerfail.fast

Modify the startup scripts to run

rshdown /etc/rshdown.conf

when the system is booted.

Author

Dirk Krause

Copyright And License

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* Neither the name of the Dirk Krause nor the names of
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