Blocking signals

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LEARN ABOUT OSF1

sigaddset

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 standards as follows:

       sigemptyset(), sigfillset(), sigaddset(), sigdelset() sigismember():  XPG4, XPG4-UNIX

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Specifies the signal set.  Specifies the individual signal.

DESCRIPTION

       The  sigemptyset(), sigfillset(), sigaddset(), sigdelset(), and sigismember() 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
       delivery 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); return_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 indicate 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)

UNIX for Dummies Questions & Answers