Let's say you're debugging something on linux. Let's say that thing crashed. What do you do? I will open gdb, load the executable and the core file and try to figure it out why the thing crashed.

Well, it's exactly what happened. But there was no core file for me. Poor me.

The defaults on OpenBSD, if I recall correctly, are to generate a core file named $prgname.core in the directory where the program was running before the crash. Also, but mind that I might be wrong, the default ulimit settings is unlimited for the core files.

So, here's a quick description on how to get that cores on linux, primarly aimed at myself:

ulimit

A ulimit -c unlimited is needed since the default may be 0. This can cause big core dumps in the $HOME if something like firefox or chrome chrashes, but I prefer to have it in .profile than to have to remember to execute the command.

pattern

On systems with systemd there should be a systemd-somethingsomething daemon and somethingsomething-ctl to manage 'em. I prefer have those cores in the directory I'm in. Bonus points if they are called like I'm used.

echo %e.core | sudo tee /proc/sys/kernel/core_pattern

%e is replaced with the program name.

However, on my machine, the core files are called $prgname.core.$pid. To disable the .pid at the end

echo 0 | sudo tee /proc/sys/kernel/core_uses_pid

And that's all!