#include <signal.h> int sigwait(const sigset_t *set, int *sig);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
The operation of sigwait() is the same as sigwaitinfo(2), except that:
The glibc implementation of sigwait() silently ignores attempts to wait for the two real-time signals that are used internally by the NPTL threading implementation. See nptl(7) for details.