In this session we will look at low-level (Linux) system debugging tools to find out what is going on (or wrong!) with your PHP environment, although the techniques are also valid for other programs besides PHP. We will cover debugging crashes with gdb, checking out memory leaks with valgrind, and many other tools to find out what is going wrong, and hopefully, figure out why. This session teaches tools to help out with tracking down bugs, and provides information on how to get better at debugging connection issues, crashes, files not being written, etc. The session is also valuable for people who want to help out with providing good bug reports for Open Source projects.