sigprocmask(2) System Calls Manual sigprocmask(2) sigprocmask, rt_sigprocmask - (libc -lc) #include /* Prototype for the glibc wrapper function */ int sigprocmask(int how, const sigset_t *_Nullable restrict set, sigset_t *_Nullable restrict oldset); #include /* Definition of SIG_* constants */ #include /* Definition of SYS_* constants */ #include /* Prototype for the underlying system call */ int syscall(SYS_rt_sigprocmask, int how, const kernel_sigset_t *_Nullable set, kernel_sigset_t *_Nullable oldset, size_t sigsetsize); /* Prototype for the legacy system call */ [[deprecated]] int syscall(SYS_sigprocmask, int how, const old_kernel_sigset_t *_Nullable set, old_kernel_sigset_t *_Nullable oldset); glibc ( feature_test_macros(7)): sigprocmask(): _POSIX_C_SOURCE sigprocmask() / . ( signal(7) ). how . SIG_BLOCK set. SIG_UNBLOCK set . . SIG_SETMASK set. oldset NULL oldset. set NULL ( how) oldset ( NULL). sigset_t (" ") sigsetops(3). sigprocmask() pthread_sigmask(3). sigprocmask() 0 . -1 errno . EFAULT set oldset . EINVAL how sigsetsize. C sigset_t C. kernel_sigset_t ( sigset_t ). glibc sigprocmask() NPTL. nptl(7) . Linux sigprocmask(). Linux 2.2 32 sigset_t ( old_kernel_sigset_t ) . rt_sigprocmask() sigset_t ( kernel_sigset_t ). size_t sigsetsize set oldset. ( sizeof(kernel_sigset_t)). sigprocmask() glibc rt_sigprocmask() . POSIX.1-2024. POSIX.1-2001. SIGKILL SIGSTOP. . . fork(2) execve(2). SIGBUS SIGFPE SIGILL SIGSEGV kill(2) sigqueue(3) raise(3). sigsetops(3) . ( ) set oldset NULL. kill(2), pause(2), sigaction(2), signal(2), sigpending(2), sigsuspend(2), pthread_sigmask(3), sigqueue(3), sigsetops(3), signal(7) 3 . . : . 6.18 8 2026 sigprocmask(2)