#!/bin/sh
# Eric Knibbe
# CS 232 - Spring 2006
# Project 2 v1.0

# Anybody Home - This shell script iterates through a list of machines in 
# the uLab, checking each with the who command to see if anyone is logged 
# on. Any unused machines are listed. Currently only works with machines 
# booted into Linux. 

echo "Available machines:"
# reads from the list of machines at the end of this file
while read hostname; do
 # Compares the output of the who command with the contents of nousers.txt, 
 # which contains the output of who when the machine is unnoccupied
 if ssh -n $hostname who | diff -q --ignore-all-space - nousers.txt > /dev/null; 
  # print the machine name if there's no one on it
  then echo "$hostname"
 fi
done <<EOF
# The following is a list of machines in the uLab. Some are currently missing 
# since they appear to be booted into Windows or down. 
stallman
noyce-kilby
sutherland
church
boole
englebart
stroustrup
atanasoff
knuth
torvalds
wirth
hollerith
leibniz
codd
chomsky
thompson
hopper
kay
goldberg
hillis
wall