Core prints information about dead processes that have
been saved as core dumps.
Core reads its arguments in order.
If a directory is encountered,
core reads every core file named
*.core in that directory.
For each core file read,
core prints the command
file, the date and time the core was generated,
the command that generated it.
stack command, if run, prints a stack trace of the
executing thread at the time of the core dump;
If no arguments are given,
core searches the directory
$COREDIR for core files;
$COREDIR is not set,
core searches the current directory.