ждать сигнала  (wait for a signal)
  
Имя (Name)
sigwait - wait for a signal
Синопсис (Synopsis)
#include <signal.h>
       int sigwait(const sigset_t *restrict set, int *restrict sig);
   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):
       sigwait():
           Since glibc 2.26:
               _POSIX_C_SOURCE >= 199506L
           Glibc 2.25 and earlier:
               _POSIX_C_SOURCE
Описание (Description)
The sigwait() function suspends execution of the calling thread
       until one of the signals specified in the signal set set becomes
       pending.  The function accepts the signal (removes it from the
       pending list of signals), and returns the signal number in sig.
       The operation of sigwait() is the same as sigwaitinfo(2), except
       that:
       * sigwait() returns only the signal number, rather than a
         siginfo_t structure describing the signal.
       * The return values of the two functions are different.
Возвращаемое значение (Return value)
On success, sigwait() returns 0.  On error, it returns a positive
       error number (listed in ERRORS).
Ошибки (Error)
EINVAL set contains an invalid signal number.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │sigwait()                             │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008.
Примечание (Note)
sigwait() is implemented using sigtimedwait(2).
       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.
Примеры (Examples)
See pthread_sigmask(3).
Смотри также (See also)
sigaction(2), signalfd(2), sigpending(2), sigsuspend(2),
       sigwaitinfo(2), sigsetops(3), signal(7)