Core dump is an operation of saving current state of a process and its memory to a file when the program crashes.

The resulting file, usually called core can be used by a programmer to find out what happend. Usually a debugger is used in the process.

In most current Linux distributions creating core files is turned off. To check, or to enable, use the «ulimit -c» command. For example, ulimit -c 0 will turn off core dumps, while ulimit -c 50000 will allow core dumps (that take up to 25000 KB). Finally, ulimit -c will allow you to view the current value for this variable.