To list number of bytes in 1k blocks:
#du -k

To list number of bytes in 512 bytes blocks:
#du -l

To list only the total disk usage in the current directory:
#du -s

To display no of free and used inodes:
#df -i

To display disk space in 1024 bytes format:
#df -k

To display disk space in MB format:
#df -m

To display disk space in GB format:
#df -g