PDR: GDB Tutorial. Go up to the Tutorials table of contents page. This tutorial is meant to get you used to using the GNU debugger, gdb. As you read through the first part of the tutorial, usually they just say, 'segmentation fault'. Part of the reason is that by default the executable file Nevertheless, this is a tutorial about segmentation faults, and on some systems, a stack overflow will be reported as a segmentation fault. (This makes sense because running out of memory on the stack will violate memory segmentation.) To diagnose a stack overflow in GDB, typically you just need to do a backtrace: The infamous "Segmentation fault" means there is some kind of invalid memory access. Unfortunately, that is all the compiler tells us. Now, let's see how we can use gdb to spot the problem(s). The strategy for debugging all of these problems is the same: load the core file into GDB, do a backtrace, move into the scope of your code, and list the lines of code that caused the segmentation fault. To get started with gdb, short examples are good. Once you know how to run it (gdb nameOfProgram), how to examine and traverse the stack (bt, up, down), see the code you're currently in (list) and how to get the values of variables (print) you're equipped to deal with the most common crashes (i.e. segFaults) and you've bootstrapped yourself to the point that you can learn more yourself. List gdb command categories: help category: List gdb commands of category: help command: Displays description of command: apropos search-word: Display commands list containing search-word in their help description: info args i args: Displays arguments of current function: info breakpoints info break info b i b: Displays list of breakpoints (gdb) run Starting program: /home/avg/c/debug Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7ab8ac1 in __strlen_sse2 () from /lib64/libc.so.6 Could you check please what output do you get? Beej's Quick Guide to GDB Release 2 (2