core dump is an essential feature to debug why a segfault happened.
It allows you to investigate a backtrace without having to run a
debugger during runtime.

Unfortunately core dumps are disabled at most distros,
you can check by using:
ulimit -c

Which prints 0 when core dumps are disabled.

First check /etc/security/limits.conf.
There should be *no* lines with core
(meaning there are no limits), or only lines
like (or a number high enough for your purposes):
*		soft	core		unlimited
*		hard	core		unlimited

Then make sure that the shell startup scripts
contain a line like (or with a number high
enough for your purposes):
ulimit -c unlimited

To investigate a core dump, use:
gdb -c dump_file ./program

It is important to pass which program generated the
core, otherwise no information is shown.