'query' shows all iperf servers which have their PIDs saved (and therefore can be stopped easily) whilst 'query-all' shows all instances of iperf (servers and clients) running on the server.

#!/bin/bash

#This script sits on an iperf server and allows simple starting and stopping off iperf.  Note, for
# stopping you need to specify the port and protocol

modeoption=$1
serverport=$2
operation=$3
mode=""

if [ "$modeoption" = "udp" ]; then
    mode="-u"
elif [ "$modeoption" = "tcp" ]; then
    mode=""
elif [ "$modeoption" = "query-all" ]; then
  /bin/ps -fC iperf
  exit 0
elif [ "$modeoption" = "query" ]; then
  /bin/ls ./iperf*.pid
  exit 0
else
   echo "usage: iperfd <tcp|udp> <port number> <start|stop>, or iperfd <query|query-all> "
   exit 0
fi

if [ "$operation" = "start" ]; then
  echo "Starting iperf on $modeoption port $serverport ..."
  /usr/bin/iperf -s -D -p $serverport $mode
  #Line below lists process IDs (-o pid), sorted by time, with no column
  # description (grep -v PID) and just the top line (head -1).  This shoudl alsways get the PID
  # of the iperf just started!
  ps -C iperf -o pid --sort=-start_time | grep -v PID | head -1 > iperf-$modeoption$serverport.pid
  echo "... done"
elif [ "$operation" = "stop" ]; then
  kill -9 `cat iperf-$modeoption$serverport.pid`
  echo "iperf server `cat iperf-$modeoption$serverport.pid` stopped"
  rm iperf-$modeoption$serverport.pid
else
   echo "usage: iperfd <tcp|udp> <port number> <start|stop>, or iperfd <query|query-all> "
   exit 0
fi

-- TobyRodwell - 24 Jul 2007