= Command Injection

Some Ruby core methods accept string data
that includes text to be executed as a system command.

They should not be called with unknown or unsanitized commands.

These methods include:

- Kernel.exec
- Kernel.spawn
- Kernel.system
- {\`command` (backtick method)}[rdoc-ref:Kernel#`]
  (also called by the expression <tt>%x[command]</tt>).
- IO.popen (when called with other than <tt>"-"</tt>).
