$ du
0       ./temp
24      .

$ du ./temp
0       ./temp

# -a stands for 'all files'
$ du -a  ./
8       ./404.html
8       ./CNAME
8       ./index.html
0       ./temp/a
0       ./temp/b
0       ./temp
24      .

# -h stands for 'human readable'
$ du -h
0B    ./temp
12K    .

# list file in order of size
$ du -a ./ | sort -n

# merge subdirectories
$ du -sh
12K    .

# display sizes of all entries in current directory
$ du -sh *
4.0K    404.html
4.0K    CNAME
4.0K    index.html
0B    temp