SYNOPSISIn signal.h Ft int Fo sigprocmask Fa int how Fa const sigset_t * restrict set Fa sigset_t * restrict oset Fc
DESCRIPTIONThe 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.
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 In signal.h :
- The new mask is the union of the current mask and the specified Fa set .
- The new mask is the intersection of the current mask and the complement of the specified Fa set .
- The current mask is replaced by the specified Fa set .
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.
The system quietly disallows SIGKILL or SIGSTOP to be blocked.
In threaded applications, pthread_sigmask3 must be used instead of Fn sigprocmask .
RETURN VALUESRv -std sigprocmask
ERRORSThe Fn sigprocmask system call will fail and the signal mask will be unchanged if one of the following occurs:
- Bq Er EINVAL
- The Fa how argument has a value other than those listed here.
STANDARDSThe Fn sigprocmask system call is expected to conform to St -p1003.1-90 .