22.14. Summary

Certain signals cause a process to create a core dump and terminate. Core dumps contain information that can be used by a debugger to inspect the state of a process at the time that it terminated. By default, a core dump file is named core, but Linux provides the /proc/sys/kernel/core_pattern file to control the naming of core dump files.

A signal may be generated asynchronously or synchronously. Asynchronous generation occurs when a signal is sent a process by the kernel or by another process. A process can’t predict precisely when an asynchronously generated signal will be delivered. (We noted that asynchronous signals are normally delivered the next time the receiving process switches from kernel mode to user mode.) Synchronous generation occurs when the process itself executes code that directly generates the signal—for example, by executing an instruction that causes a hardware exception or by calling raise(). The delivery of a synchronously generated signal is precisely predictable (it occurs immediately).