Function

sigprocmask invokes the sigprocmask callable service to examine or change the calling thread's signal mask.

Parameters

number

To specify the action to be taken on the thread's signal mask, you can specify a numeric value (see REXX predefined variables) or the predefined variable beginning with SIG_ used to derive the appropriate numeric value. Use one of the following predefined variables:

Variable	Description
SIG_BLOCK	Add the signals in new_mask to those to be blocked for this thread.
SIG_SETMASK	Replace the thread's signal mask with new_mask.
SIG_UNBLOCK	Delete the signals in new_mask from those blocked for this thread.

new_mask

The new signal mask, a string of 64 characters with values 0 or 1. The first character represents signal number 1. A string shorter than 64 characters is padded on the right with zeros. Mask bits set on represent signals that are blocked. For more information on signals, see Using the REXX signal services.

variable

The name of the buffer that will store the old signal mask, a string of 64 characters with values 0 or 1, representing the 64 bits in a signal mask. Mask bits set on represent signals that are blocked. A zero indicates that no signal mask was returned.

Usage notes

1. The sigprocmask service examines, changes, or both examines and changes the signal mask for the calling thread. This mask is called the thread's signal mask. If there are any pending unblocked signals, either at the process level or at the current thread's level after changing the signal mask, at least one of the signals is delivered to the thread before the sigprocmask service returns.
2. You cannot block the SIGKILL and the SIGSTOP signals. If you call the sigprocmask service with a request that would block those signals, that part of your request is ignored and no error is indicated.
3. A request to block signals that are not supported is accepted, and a return value of zero is returned.
4. All pending unblocked signals are moved from the process level to the current thread.