Here are the instructions to install HHVM on Ubuntu 12.04.
sudo add-apt-repository ppa:mapnik/boost wget -O - http://dl.hhvm.com/conf/hhvm.gpg.key | sudo apt-key add - echo deb http://dl.hhvm.com/ubuntu precise main | sudo tee /etc/apt/sources.list.d/hhvm.list sudo apt-get update sudo apt-get install hhvm
To test if your HHVM is installed, save the following into a file called test.php. Notice there is NO closing tag for hh.
<?hh print "hellon";
Then run hhvm test.php, you should see the hello string gets printed out.