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@(#)sigprocmask.2 8.1 (Berkeley) 6/4/93
$FreeBSD: head/lib/libc/sys/sigprocmask.2 165903 2007-01-09 00:28:16Z imp $
.Dd June 4, 1993 .Dt SIGPROCMASK 2 .Os .Sh NAME .Nm sigprocmask .Nd manipulate current signal mask .Sh LIBRARY .Lb libc .Sh SYNOPSIS n signal.h .Ft int .Fo sigprocmask .Fa "int how" .Fa "const sigset_t * restrict set" .Fa "sigset_t * restrict oset" .Fc .Sh DESCRIPTION The .Fn sigprocmask system call 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 signal mask set.
p If .Fa set is not null, the action of .Fn sigprocmask depends on the value of the .Fa how argument. The signal mask is changed as a function of the specified .Fa set and the current mask. The function is specified by .Fa how using one of the following values from n signal.h : l -tag -width SIG_UNBLOCK t Dv SIG_BLOCK The new mask is the union of the current mask and the specified .Fa set . t Dv SIG_UNBLOCK The new mask is the intersection of the current mask and the complement of the specified .Fa set . t Dv SIG_SETMASK The current mask is replaced by the specified .Fa set . .El
p If .Fa oset is not null, it is set to the previous value of the signal mask. When .Fa set is null, the value of .Fa how is insignificant and the mask remains unset providing a way to examine the signal mask without modification.
p The system quietly disallows .Dv SIGKILL or .Dv SIGSTOP to be blocked. .Sh RETURN VALUES .Rv -std sigprocmask .Sh ERRORS The .Fn sigprocmask system call will fail and the signal mask will be unchanged if one of the following occurs: l -tag -width Er t Bq Er EINVAL The .Fa how argument has a value other than those listed here. .El .Sh SEE ALSO .Xr kill 2 , .Xr sigaction 2 , .Xr sigpending 2 , .Xr sigsuspend 2 , .Xr fpsetmask 3 , .Xr sigsetops 3 .Sh STANDARDS The .Fn sigprocmask system call is expected to conform to .St -p1003.1-90 .