Picking up right where we left off in our previous exercises. We’ve got a core due to an error. We fix the error by removing line 31 from myprog.c and rebuilding. The program runs now… prints out some text and pauses… to simulate a long-running program that we need to debug without disrupting too much. Let’s get a core! # UMEM_DEBUG=default ./myprog &  74502 read 25144 words. # echo '::gcore' | mdb -p `pgrep myprog` mdb: core.
So what’s this all about then? Debugging. I’ve written a lot of C, I still write a lot of C and I sure as hell end up debugging a lot of C. One thing that pisses me off is when I’ve got a core file, but I’ve no idea about the exact version or build of the ELF binary that produced it. The bottom line is that I still need to find the failure.