Topic summary
SIGCHLD
Extracted from the Wikipedia article Child process.
End of life
POSIX.1-2001 allows a parent process to elect for the kernel to automatically reap child processes that terminate by explicitly setting the disposition of SIGCHLD to SIG_IGN (although ignore is the default, automatic reaping only occurs if the disposition is set to ignore explicitly), or by setting the SA_NOCLDWAIT flag for the SIGCHLD signal. Linux 2.6 kernels adhere to this behavior, and FreeBSD supports both of these methods since version 5.0. However, because of historical differences between System V and BSD behaviors with regard to ignoring SIGCHLD, calling wait remains the most portable paradigm for cleaning up after forked child processes.