sigsett

Sigsett is a term commonly used to refer to a set of signals managed by POSIX-compliant systems. The canonical representation of a signal set is the type sigset_t, an opaque data type defined by the POSIX standard. A sigset represents a collection of signals that can be blocked, unblocked, or tested as a group during program execution.

A sigset is manipulated with a small, standardized API. Typical operations include initializing the set with sigemptyset (empty set) or sigfillset (all signals), adding a signal with sigaddset, removing a signal with sigdelset, and testing membership with sigismember. Some systems also provide set operations such as sigorset (set union) and sigandset (set intersection), and signotset to complement a set.

The primary use of a sigset is to control signal delivery. It is used with sigprocmask or pthread_sigmask to change the process or thread signal mask, thereby blocking or unblocking signals. A sigset is also supplied to sigaction via the sa_mask field to specify signals that should be blocked while a signal handler is executing.

Sigsets are portable across POSIX-compliant platforms, though internal representations vary by implementation. In practice, developers manipulate sigset_t objects rather than relying on any specific bit-level layout. Note that sigsett is not a separate standard term; the authoritative terminology is sigset or sigset_t. If you encounter sigsett in code, it is typically a variant spelling of the same concept.