#!/bin/bash
#Copyright 2000 William Stearns <wstearns@pobox.com>
#GPL'd, of course.
#Version 0.1, 4/6/2000

#Usage: fanout "MACHINES" "commands and parameters to run on each machine"
#Examples:
#	fanout "wstearns@localhost localhost anotherhost.someplace.net" \
#	 "echo My PID is \"\$PPID\" ; sleep 15"
#
#	fanout "localhost" "uname -a ; rpm -qa | egrep -i '(openlinux|redhat-release)' \
#	 ; uptime ; df -P / ; netstat -a | grep '*:*'" | less
#
#	fanout "localhost myaccount@localhost" "uptime" >uptime-sample
#
#Notes:
#- The accounts you connect to should have your ssh key ready and you should be
#running ssh-agent ready to serve that key.
#- The command(s) you execute run concurrently on each remote machine.  Output
#does not show up until all are done.
#- Sample run is at the end of the script.

MYPID="$$"
TARGETS=`echo "$1" | tr ' ' '\012' | sort | uniq`	#Sort and remove dupes
shift												#Leave just the commands and params to be executed.
STARTTIME=`date`
for ONETARGET in $TARGETS ; do
	case $ONETARGET in
	*@*)											#user@machine form
		ONEUSER="-l ${ONETARGET%%@*}"
		ONEMACH=${ONETARGET##*@}
		HEADER="==== As ${ONETARGET%%@*} on $ONEMACH ===="
		;;
	*)												#just machine form
		ONEUSER=""
		ONEMACH=$ONETARGET
		HEADER="==== On $ONEMACH ===="
		;;
	esac

	if ping -c 4 $ONEMACH >/dev/null 2>/dev/null ; then
		echo Starting $ONETARGET >/dev/stderr		#Machine is reachable
		#Show machine name header, show command output, indented two spaces, save all to a temp file.
		( echo $HEADER ; ssh -n $ONEUSER $ONEMACH "$*" | sed -e 's/^/  /' ; echo ) >/tmp/output.$MYPID.$! &
	else
		echo $ONETARGET unavailable >/dev/stderr	#Machine not responding
		( echo $HEADER ; echo "==== Machine unreachable by ping" ; echo ) >/tmp/output.$MYPID.$! &
	fi
	BACKPIDS="$BACKPIDS $!"							#Remember the PID for later retrieval
done
wait												#Until everyone's done.

echo Fanout executing \"$*\"
echo Start time $STARTTIME , End time `date`
for ONEPID in $BACKPIDS ; do
	cat /tmp/output.$MYPID.$ONEPID
	rm -f /tmp/output.$MYPID.$ONEPID
done

#Sample run
#[wstearns@sparrow fanout]$ ./fanout "localhost wstearns@localhost aaa.bbb.ccc" "uptime" | less
#aaa.bbb.ccc unavailable
#Starting localhost
#Starting wstearns@localhost
#Fanout executing "uptime"
#Start time Fri Apr 7 00:13:07 EDT 2000 , End time Fri Apr 7 00:13:20 EDT 2000
#==== On aaa.bbb.ccc ====
#==== Machine unreachable by ping
#
#==== On localhost ====
#   12:13am  up 3 days, 10:44,  0 users,  load average: 0.17, 0.17, 0.22
#
#==== As wstearns on localhost ====
#   12:13am  up 3 days, 10:44,  0 users,  load average: 0.15, 0.16, 0.22