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sigemptyset(3) Library Functions Manual sigemptyset(3) NAME sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - Creates and manipulates signal masks LIBRARY Standard C Library (libc.so, libc.a) SYNOPSIS #include <signal.h> int sigemptyset ( sigset_t *set); int sigfillset ( sigset_t *set); int sigaddset ( sigset_t *set, int sig_number ); int sigdelset ( sigset_t *set, int sig_number ); int sigismember ( sigset_t *set, int sig_number ); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: sigemptyset(), sigfillset(), sigaddset(), sigdelset() sigismem- ber(): XPG4, XPG4-UNIX Refer to the standards(5) reference page for more information about in- dustry standards and associated tags. PARAMETERS Specifies the signal set. Specifies the individual signal. DESCRIPTION The sigemptyset(), sigfillset(), sigaddset(), sigdelset(), and sigis- member() functions manipulate sets of signals. These functions operate on data objects that can be addressed by the application, not on any set of signals known to the system, such as the set blocked from deliv- ery to a process or the set pending for a process. The sigemptyset() function initializes the signal set pointed to by the set parameter such that all signals are excluded. The sigfillset() function initializes the signal set pointed to by the set parameter such that all signals are included. A call to either the sigfillset() or sigemptyset() function must be made at least once for each object of the type sigset_t prior to any other use of that object. The sigaddset() and sigdelset() functions respectively add and delete the individual signal specified by the sig_number parameter from the signal set specified by the set parameter. The sigismember() function tests whether the sig_number parameter is a member of the signal set pointed to by the set parameter. EXAMPLES To generate and use a signal mask that blocks only the SIGINT signal from delivery, enter: #include <signal.h> int return_value; sigset_t newset; . . . sigemptyset(&newset); sigaddset(&newset, SIGINT); re- turn_value = sigprocmask (SIG_SETMASK, &newset, NULL); RETURN VALUES Upon successful completion, the sigismember() function returns a value of 1 if the specified signal is a member of the specified set, or a value of 0 (zero) if it is not. Upon successful completion, the other functions return a value of 0. For all the preceding functions, if an error is detected, a value of -1 is returned and errno is set to indi- cate the error. ERRORS The sigfillset(), sigdelset(), sigismember(), and sigaddset() functions set errno to the specified values for the following conditions: The value of the sig_number parameter is not a valid signal number. RELATED INFORMATION Functions: sigaction(2), sigprocmask(2), sigsuspend(2), sigvec(2) Files: signal(4) Standards: standards(5) delim off sigemptyset(3)