Solutions to HW 7
------------------

#!/bin/bash

if [ "$#" -ne 1 ]
then
    echo "`basename $0`: Improper argument usage." 1>&2
    exit 1
fi

if [ ! -d $1 ]
then
    echo "$1 is not a directory." 1>&2
    exit 2
fi

cd "$1"
dirname=`pwd`

traverse ()
{
	local dir=$1
        local level=$2
        local i
        local prefix
        local base
        local formattedstring
        local newname

        prefix=""
        for i in `seq 1 $level`
        do
          prefix=$prefix"+"
        done
        base=`basename $dir`
        formattedstring=$prefix$base
        echo $formattedstring
        for i in `ls $dir`
        do
	   newname=$dir"/"$i
           if [ -f $newname ]
           then
              echo $prefix"-""`basename $i`"
           fi
           if [ -d $newname ]
           then
               traverse $newname `expr $level + 1`
           fi
        done
}

traverse $dirname 1