This is a shell program. What is the for loop doing?
#!/ usr / bin / sh

path=/u/csc209h/winter/pub/shell-prog

upper_bound=7

for i in `seq 1 "$upper_bound"`
do
    prev=`expr $i - 1`
    next=`expr $i + 1`
    if (! diff "${path}/${i}" "${path}/${prev}" > /dev/null) &&
        (! diff "${path}/${i}" "${path}/${prev}" > /dev/null)
    then
        echo "${path}/${i}" is the odd one out
#Can exit here
        exit 0
    fi
done