How to crash Linux?

As root, you can do whatever you want.

Try this command, as root (reconsider if you really want to crash):

# cp /dev/zero /dev/men

As root, you can even erase all the files on your system with a similarly innocuously looking one-liner (don’t do it):

# rm -rf /

This is not to say that Linux is easy to crash, but that the system administrator (”root”) has the complete power over the system so think before when working on Linux as “root” user.