Shows the disk usage of the current working directory. Each file in the directory and it's usage (in blocks) is displayed.

du -k

Shows the usage of the current directory in 1024-byte units (kilobytes).

du /home/fred

Shows the disk usage of the /home/fred subdirectory.

du -ks /home/fred

Shows only a summary of the disk usage of the /home/fred subdirectory (measured in kilobytes).

du -ks /home/fred/*

Shows a summary of the disk usage of each subdirectory of /home/fred (measured in kilobytes).