#!/bin/sh
#
# -------------------------------------------------------------
# Get the real disk usage for a group of selected files
#
# This script counts the size of the files and directories
# listed, but exclude files that have hard links referenced outside 
# the list. 
#
# The undelying objective of this script is to report the
# real amount of disk used for backup solutions that are heavily
# using hard links to save disk space on identical files (I use
# ccollect, but this likely works with rsnapshot)
# -------------------------------------------------------------
# 20091002 - initial release - pdrolet (rdu@drolet.name)
 
# --------------------
# Parse options
# --------------------
# Known problem:
# - Command line cannot get a directory with a space in it
#
kdivider=1
find_options=""
while [ "$#" -ge 1 ]; do
   case "$1" in
     -m)
       kdivider=1024
       ;;
     -g)
       kdivider=1048576
       ;;
     -h|--help)
       echo
       echo $0: \<directories\> \[options below and any \"find\" options\]
       echo \ \ -m: result in mega bytes \(rounded up\)
       echo \ \ -g: result in giga bytes \(rounded up\)
       echo \ \ -h: this help
       echo
       exit 0
       ;;
     *)
       find_options="${find_options} $1"
       ;;
   esac
   shift
done

# ------------------------------------------------------------------------------------------------------
# Compute the size
# ------------------------------------------------------------------------------------------------------
# 1) Find selected files and list link count, inodes, file type and size
# 2) Sort (sorts on inodes since link count is constant per inode)
# 3) Merge duplicates using uniq 
#    (result is occurence count, link count, inode, file type and size)
# 4) Use awk to sum up the file size of each inodes when the occurence count
#    and link count are the same.  Use %k for size since awk's printf is 32 bits 
# 5) Present the result with additional dividers based on command line parameters
# 
echo $((( `find ${find_options} -printf '%n %i %y %k \n' \
       | sort -n \
       | uniq -c \
       | awk '{ if (( $1 == $2 ) || ($4 == "d")) { sum += $5; } } END { printf "%u\n",(sum); }'` \
       + ${kdivider} -1 ) / ${kdivider} ))