Do you want to know the size of a directory in Linux? Use the du command.

du -sh

Explanation

The du command estimates the space used by a directory.

The options -sh are (from man du):

  -s, --summarize
         display only a total for each argument

  -h, --human-readable
         print sizes in human readable format (e.g., 1K 234M 2G)

To check more than one directory and get the total size of those directories, use

du -sch *

What does the extra option mean?

  -c, --total
         produce a grand total

Include hidden files?

du -sch * .*

Want to know how much disk space has been used?

du -h .