IBM Developer works has published a simple howto/guide that will gain you a quality knowledge while exploring your UNIX system.
FTA, "...Programming a UNIX system can be fun as well as educational. With the UNIX strace tool and GDB, the GNU Project Debugger, you can really dig deep into the functionality of your system and learn a lot about the various programs that comprise it. Using both tools in concert can be a rewarding experience as you look under the hood of your UNIX machine.
The UNIX family has always provided abundantly for its users. UNIX is a treasure chest of tools with which you can not only do productive work but also educate and entertain yourself as you explore the depths of the operating system. Two useful tools for this purpose are strace, with which you can trace the system calls of any program, and the GDB Debugger, which is a full-featured debugger that allows you to run programs in a controlled environment...".