This problem was infuriating. After having upgraded my Vagrant Box to run PHP 5.6, I was looking forward to trying out phpdbg, the new built in debugger that ships with PHP 5.6.
It turns out that Debian use their own moronic naming system for their PHP package commands. I was typing in phpdbg into the shell, and all I got in return was ‘command not found’.
I tried sudo apt-get install php5-phpdbg, yet it told me that it was already the latest version!
I eventually found it in the /usr/bin folder, under the name php5dbg. Why?
For reference, you can run this command to help find it: (if dpkg is installed)
dpkg -L <pkgname> | grep '/bin/'
What a waste of time, I hope this helps someone.