There are two ways to install the tools:

Download phar file

or if you have problems with SSL certificate:

You can make the .phar file executable.

If you want to use command system wide you can copy it to /usr/local/bin.

Debian / suhosin:

On some debian systems with compiled in suhosin the phar extension must be added to a whitelist.

Add this to your php.ini file:

You don’t like the filename?

Just rename it to whatever you want.

Install with Composer