pfind takes a pid as its argument and returns a pointer to the
.Vt proc structure whose PID is specified in the argument only if the pid is on the allproc list.
zpfind takes a pid as its argument. If zpfind finds a process whose PID is equal to that of argument and is a zombie process, meaning that it must reside on the zombproc list, zpfind returns a pointer to that
.Vt proc structure.
Both pfind and zpfind lock the
.Vt proc structure that is returned using PROC_LOCK "p".
pfind and zpfind return a pointer to a
.Vt proc structure on success and a NULL on failure.