How to find the directory that occupies the most disk space?

I bought a cheap vps with a small disk space. After running for some time, it says the disk is full. How can I figure out which directory consumes the most disk space so I can deal with it(like deleting some junk files)?
You can use the command du -k to check the disk space occupation of every directory or go to each directory to issue du -sk.
For experienced webmasters, checking the following directories often gives you the answer:

  • Your website’s home directorie, if your website saves a lot of static files.
  • The temporary directories: /tmp, /var/tmp.
  • /home/ directory which is used by many software to put data in.
  • /var/lib/mysql/, which is used by mysql to save database files. The size of this directory keeps increasing if your website stores data in databases. This directory is often ignored if you are not familiar with mysql.
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