PTHREAD_KILL(3) Library Functions Manual PTHREAD_KILL(3)

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:
[]
sig is an invalid or unsupported signal number.
[]
thread is an invalid thread ID.

kill(2), sigwait(2), pthread_self(3), raise(3)

The function conforms to IEEE Std 1003.1-2001 (“POSIX.1”).
July 9, 2010 NetBSD 9.2