sigprocmask(3-thr)                                       sigprocmask(3-thr)

NAME
     sigprocmask - examines and changes blocked signals (POSIX software
     signal facilities)

SYNOPSIS
     #include <signal.h>

     int sigprocmask(int how, const sigsett *set, sigsett *oset);

PARAMETERS
     how       The manner in which the values in set are changed as defined
               by one of the described argument values.

     set       A set of signals that will be used to change the current
               thread's signal mask according to the value in the how
               parameter.

     oset      Points to a location in which the signal mask in effect at
               the time of the sigprocmask() function call is returned.

DESCRIPTION
     The sigprocmask() function is used to examine or change (or both) the
     signal mask of the calling process. If the value of the argument set
     is not NULL, it points to a set of signals to be used to change the
     currently blocked set according to the how parameter as follows:

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

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

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

     If the argument oset is not NULL, the previous mask is stored in the
     space pointed to by oset.

     The sigprocmask() function can be used to inquire about the currently
     blocked signals by specifying a null pointer for set, since the value
     of the argument how is not significant and the signal mask of the pro-
     cess is unchanged unless this parameter is not a null pointer. In
     order for the signal mask in effect at the time of the sigprocmask()
     call to be returned, the oset argument must not be a null pointer.







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sigprocmask(3-thr)                                       sigprocmask(3-thr)

     If there are any pending unblocked signals after the call to the
     sigprocmask() function, at least one of those signals shall be
     delivered before the sigprocmask() function returns. As a system
     restriction, the SIGKILL and SIGSTOP signals cannot be blocked.

     If the sigprocmask() function fails, the signal mask of the process is
     not changed by this function call.

RETURN VALUES
     Possible return values are as follows:

     EINVAL    The value specified by the how parameter is not equal to one
               of the defined values. The signal mask of the process
               remains unchanged.

SEE ALSO
     sigsuspend(2), sigaction(3-thr), sigpending(3-thr), sigsetops(3C),
     signal(5).




































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