How to check which directory used up most of the disk space?
For example, assume you are at /usr/local, you want to generate a report on disk space usage on all the sub directories, you can use the following command
# du -k * | sort -n . . 14564 share/man/man3 14816 share/man 16624 share/perl/5.10.0 16628 share/perl 33060 share
It will give you a very clear and useful report.