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Pthread Library
HP-UX 11i Version 3: February 2007

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pthread_sigmask() — examine/change signal mask of calling thread


#include <pthread.h>

int pthread_sigmask( int how, const sigset_t *__restrict set, sigset_t *__restrict oset );



This parameter defines how the signal mask of the calling thread will be changed.


Pointer to the set of signals that will be used to change the currently blocked signal set.


Pointer to where the previous signal mask will be returned.


pthread_sigmask() allows the calling thread to examine and/or change its signal mask.

Unless it is a null pointer, the argument set points to a set of signals which are to be used to change the currently blocked signal set.

The argument how indicates how the set is changed. The legal values are:


The resulting set is the union of the current set and the signal set pointed to by set.


The resulting set is the intersection of the current set and the complement of the signal set pointed to by set.


The resulting set is the signal set pointed to by set.

If the argument oset is not a null pointer, the previous signal mask is returned in oset. If set is a null pointer, the value of the argument how is insignificant and the thread's signal mask is unchanged; thus, the call can be used to inquire about currently blocked signals.

If there any pending unblocked signals after the call to pthread_sigmask(), at least one of those signals is delivered before the call to pthread_sigmask() returns.

It is impossible to block the SIGKILL or SIGSTOP signal. This is enforced by the system without causing an error to be indicated.

The thread's signal mask is not changed if pthread_sigmask() fails for any reason.


Upon successful completion, pthread_sigmask() returns zero. Otherwise, an error number is returned to indicate the error (the errno variable is not set).


If any of the following occur, the pthread_sigmask() function returns the corresponding error number:


how contains an invalid value.


set or oset points to an invalid address. The reliable detection of this error is implementation dependent.


pthread_sigmask() was derived from the IEEE POSIX P1003.1c standard.


pthread_sigmask(): POSIX 1003.1c.

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