Adds the specified individual signal.

    Format

      #include  <signal.h>

      int sigaddset  (sigset_t *set, int sig_number);

1 - Arguments

 set

    The signal set.

 sig_number

    The individual signal.

2 - Description

    The sigaddset function manipulates sets of signals. This function
    operates on data objects that you can address by the application,
    not on any set of signals known to the system. For example, this
    function does not operate on the set blocked from delivery to a
    process or the set pending for a process.

    The sigaddset function adds the individual signal specified by
    sig_number from the signal set specified by set.

3 - Example

      The following example shows how to generate and use a signal
      mask that blocks only the SIGINT signal from delivery:

               #include <signal.h>
               int return_value;
               sigset_t newset;
                 . . .
               sigemptyset(&newset);
               sigaddset(&newset, SIGINT);
               return_value = sigprocmask (SIG_SETMASK, &newset, NULL);

4 - Return Values

    0                  Indicates success.
    -1                 Indicates an error; errno is set to the
                       following value:

                       o  EINVAL - The value of sig_number is not a
                          valid signal number.