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How to get the Unix rwhod service to start at boot time on a Mac; and how to use the commands to get information from it.

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Last updated: 2 October 2009

The rwhod daemon is a Unix service which monitors the status of other machines on the local network, and provides this information to the local client programs rwho and ruptime.

Mac OS X includes the rwhod daemon and the user commands, but it does not come configured so that the daemon starts at boot time. The instructions

Running rwhod at start-up

1. Become the super-user or log in as the Administrator.

2. In the folder /Library/StartupItems create a sub-folder called rwhod

3. In that folder you put these two files:

   StartupParameters.plist contains:

   {
     Description     = "rwho/ruptime  system";
     Provides        = ("rwhod");
     Requires        = ("Resolver");
     OrderPreference = "None";
     Messages =
     {
       start = "Starting rwho daemon";
       stop  = "Stopping rwho daemon";
     };
   }
   

   rwhod contains:

   #!/bin/sh
   #
   # Start the rwhod at system startup time on MacOSX
   #
   # Eric Myers  - 23 July 2003
   # @(#) $Id:$
   ######################################################################
   
   . /etc/rc.common
   
   # Add 'status' option 
   
   RunService ()
   {
       case $1 in 
         start  ) StartService   ;;
         stop   ) StopService    ;;
         restart) RestartService ;;
         status ) StatusReport   ;;
         *      ) echo "$0: unknown argument: $1";;
       esac
   }
   
   StatusReport ()
   {
       PID=`ps ax | grep -v grep | awk '$5 ~ /\/rwhod$/ {print $1}'`
       if [ "$PID" != "" ]; then
          echo "rwhod (pid $PID) is running... "
          exit 0
       else
          if [ -f /var/run/rwhod.pid ]; then
             echo "rwhod is stopped but pid file exists."
   	  exit 1
          else
             echo "rwhod is stopped "
   	  exit 2
          fi
       fi
   }
   
   
   StartService ()
   {
       CheckForNetwork 
       if [ "${NETWORKUP}" = "-NO-" ]; then exit; fi
   
       if [ ! -x /usr/sbin/rwhod ]; then exit; fi
   
       ConsoleMessage "Starting rwho daemon"
       /usr/sbin/rwhod
   
       # Create pid file
       PID=`ps ax | grep -v grep | awk '$5 ~ /rwhod/ {print $1} '`
       echo $PID > /var/run/rwhod.pid
   }
   
   StopService ()
   {
       PID=`ps ax | grep -v grep | awk '$5 ~ /\/rwhod$/ {print $1}'`
       if [ "$PID" != "" ]; then
           ConsoleMessage "Stopping rwho daemon"
           kill -TERM "${PID}"
           rm -f /var/run/rwhod.pid
       else
           echo "rwhod is not running."
       fi
   }
   
   RestartService ()
   {
       StopService
       StartService
   }
   
   
   RunService "$1"
   
   ##
   

4. Make the rwhod file executable.

5. Reboot.

Using the commands

ruptime

The ruptime command produces a listing of status information about machines on the local network. It is in some sense a remote version of the Unix "uptime" command.

rwho

The rhow command lists the active users on machines on the local network. In general it omits users who have been idle for over an hour, unless you include the -a flag.

Remote monitoring