SIGPROCMASK(2) UNIX Programmer's Manual SIGPROCMASK(2) NAME sigprocmask - manipulate current signal mask SYNOPSIS #include _i_n_t sigprocmask(how, set, oset) _i_n_t _h_o_w; _s_i_g_s_e_t__t *_s_e_t; _s_i_g_s_e_t__t *_o_s_e_t; _s_i_g_s_e_t__t sigmask(signum) _i_n_t _s_i_g_n_u_m; DESCRIPTION The sigprocmask function examines and/or changes the current signal mask (those signals that are blocked from delivery). Signals are blocked if they are members of the current sig- nal mask set. If _s_e_t is not null, the action of sigprocmask depends on the value of the parameter _h_o_w. The signal mask is changed as a function of the specified _s_e_t and the current mask. The function is specified by _h_o_w using one of the following values from <_s_i_g_n_a_l._h>: SIG_BLOCK The new mask is the union of the current mask and the specified _s_e_t. SIG_UNBLOCK The new mask is the intersection of the current mask and the complement of the specified _s_e_t. SIG_SETMASK The current mask is replaced by the specified _s_e_t. If _o_s_e_t is not null, it is set to the previous value of the signal mask. When _s_e_t is null, the value of _h_o_w is insigni- ficant and the mask remains unset providing a way to examine the signal mask without modification. The system quietly disallows SIGKILL or SIGSTOP to be blocked. RETURN VALUES A 0 value indicated that the call succeeded. A -1 return value indicates an error occurred and _e_r_r_n_o is set to indi- cated the reason. Printed 11/26/99 September 3, 1997 1 SIGPROCMASK(2) UNIX Programmer's Manual SIGPROCMASK(2) ERRORS The sigprocmask call will fail and the signal mask will be unchanged if one of the following occurs: EINVAL _h_o_w has a value other than those listed here. EFAULT _s_e_t or _o_s_e_t contain an invalid address. SEE ALSO kill(2), sigaction(2), sigsetops(3), sigsuspend(2) STANDARDS The sigprocmask function call is expected to conform to IEEE Std1003.1-1988 (``POSIX''). Printed 11/26/99 September 3, 1997 2