pthread_kill —
send a signal to a specified thread
POSIX Threads Library (libpthread, -lpthread)
#include <pthread.h>
#include <signal.h>
int
  
  pthread_kill(pthread_t
    thread, int
  sig);
The pthread_kill() function sends a signal, specified by
  sig, to a thread, specified by
  thread. The signal will be handled in the context of
  thread, but the signal action may alter the process as a
  whole. If sig is 0, error checking is performed, but no
  signal is actually sent.
If successful, pthread_kill() returns 0. Otherwise, an
  error number is returned.
pthread_kill() shall fail if:
  - [EINVAL]
- sig is an invalid or unsupported signal number.
- [ESRCH]
- thread is an invalid thread ID.
The function conforms to IEEE Std 1003.1-2001
  (“POSIX.1”).