du -h -c /root | grep total | awk '{print $1}'

cd /usr/local/bin/
touch dirsize
nano dirsize
# oder vi dirsize
# Quellcode einfügen und abspeichern
chmod +x dirsize

# Ordnergröße in Bytes:
dirsize /root
 
# Ordnergröße in "lesbarem" Format mit Einheit (bspw. 1K 234M 2G)
dirsize -h /root
 
# Wie -h, verwendet zur Umrechnung aber 1000er-Blöcke
# => SI-Einheiten anstatt 1024-System
dirsize -si /root

#!/bin/bash
 
#################################################################
#                                                               #
# dirsize - displays the filesize of a directory                #
#                                                               #
# @author  Tobias Fischer / info (at) mediaversal (dot) de      #
# @link    http://tobias-bloggt.de/?p=763                       #
# @date    2011-06-03                                           #
# @version 1.0                                                  #
# @licence CC Attribution-Share Alike 3.0                       #
#          http://creativecommons.org/licenses/by-sa/3.0/       #
#################################################################
 
# display help text
helptext () {
        echo ""
        echo "Usage: $0 [-h|-si|-b] directory"
        echo ""
        echo "       -h  directoy  : print sizes in human readable format (e.g., 1K 234M 2G)"
        echo "       -si directory : like -h, but use powers of 1000 not 1024"
        echo "       -b  directory : display the directory size in bytes (standard if no option)"
        echo "       --help        : display this help text"
        echo ""
}
 
# check first parameter (should be an option)
case $1 in
  -[Hh])
        # display size in human readable format
        du -h -c $2 | grep total | awk '{print $1}'
        ;;
  -[Ss][Ii])
        # display size in human readable format
        du --si -c $2 | grep total | awk '{print $1}'
        ;;
  -[Bb])
        # display size in bytes
        du -c $2 | grep total | awk '{print $1}'
        ;;
  --help)
        # display help text
        helptext
        ;;
  *)
        if [ $# -eq 0 ] ; then
 
                echo ""
                echo "ERROR! Bad arguments!"
 
                # display help text
                helptext
 
                exit 1
        else
                # no option set, take first parameter as directory
                # same as -b
                du -c $1 | grep total | awk '{print $1}'
        fi
        ;;
esac