What Is a "core" File?
A core file is created when a program terminates unexpectedly, due to
a bug, or a violation of the operating system's or hardware's
protection mechanisms. The operating system kills the program and
creates a core file that programmers can use to figure out what went
wrong. It contains a detailed description of the state that the
program was in when it died.
If would like to determine what program a core file came from, use the
file command, like this:
$ file core
That will tell you the name of the program that produced the core
dump. You may want to write the maintainer(s) of the program, telling
them that their program dumped core.