Listing 1. Shell Script for Use in Prompt

#!/bin/bash

# lsbytesum - sum the number of bytes in a 
# directory listing
TotalBytes=0
# cut below could fail - sed would be a good
# alternative?
for Bytes in $(ls -l | grep "^-" | cut
-c30-41)
do
    let TotalBytes=$TotalBytes+$Bytes
done
TotalMeg=$(echo -e "scale=3 \n$TotalBytes/1048576\
  \nquit" | bc)
echo -n "$TotalMeg"