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signal(3ucb) [sunos man page]

signal(3UCB)					     SunOS/BSD Compatibility Library Functions					      signal(3UCB)

NAME
signal - simplified software signal facilities SYNOPSIS
/usr/ucb/cc [ flag ... ] file ... #include <signal.h> void (*signal(sig, func))(); int sig; void (*func)(); DESCRIPTION
signal() is a simplified interface to the more general sigvec(3UCB) facility. Programs that use signal() in preference to sigvec() are more likely to be portable to all systems. A signal is generated by some abnormal event, initiated by a user at a terminal (quit, interrupt, stop), by a program error (bus error, etc.), by request of another program (kill), or when a process is stopped because it wishes to access its control terminal while in the background (see termio(7I)). Signals are optionally generated when a process resumes after being stopped, when the status of child pro- cesses changes, or when input is ready at the control terminal. Most signals cause termination of the receiving process if no action is taken; some signals instead cause the process receiving them to be stopped, or are simply discarded if the process has not requested other- wise. Except for the SIGKILL and SIGSTOP signals, the signal() call allows signals either to be ignored or to interrupt to a specified location. See sigvec(3UCB) for a complete list of the signals. If func is SIG_DFL, the default action for signal sig is reinstated; this default is termination (with a core image for starred signals) except for signals marked with o or a dagger.. Signals marked with o are discarded if the action is SIG_DFL; signals marked with a dagger cause the process to stop. If func is SIG_IGN the signal is subsequently ignored and pending instances of the signal are discarded. Other- wise, when the signal occurs further occurrences of the signal are automatically blocked and func is called. A return from the function unblocks the handled signal and continues the process at the point it was interrupted. If a caught signal occurs during certain functions, terminating the call prematurely, the call is automatically restarted. In particular this can occur during a read(2) or write(2) on a slow device (such as a terminal; but not a file) and during a wait(3C). The value of signal() is the previous (or initial) value of func for the particular signal. After a fork(2) or vfork(2) the child inherits all signals. An exec(2) resets all caught signals to the default action; ignored signals remain ignored. RETURN VALUES
The previous action is returned on a successful call. Otherwise,-1 is returned and errno is set to indicate the error. ERRORS
signal() will fail and no action will take place if the following occurs: EINVAL sig is not a valid signal number, or is SIGKILL or SIGSTOP. SEE ALSO
kill(1), exec(2), fcntl(2), fork(2), getitimer(2), getrlimit(2), kill(2), read(2), sigaction(2), write(2), abort(3C), ptrace(3C), setjmp(3C), setjmp(3UCB), sigblock(3UCB), signal(3C), signal.h(3HEAD), sigstack(3UCB), sigvec(3UCB), wait(3C), wait(3UCB), termio(7I) NOTES
Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system libraries or in multi-threaded applications is unsupported. The handler routine func can be declared: void handler(signum) int signum; Here signum is the signal number. See sigvec(3UCB) for more information. SunOS 5.10 10 Jan 1996 signal(3UCB)

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sigblock(3UCB)					     SunOS/BSD Compatibility Library Functions					    sigblock(3UCB)

NAME
sigblock, sigmask, sigpause, sigsetmask - block signals SYNOPSIS
/usr/ucb/cc [ flag ... ] file ... #include <signal.h> int sigblock(mask); intmask; int sigmask( signum); int signum; int sigpause(int mask); int mask; int sigsetmask( mask); int mask; DESCRIPTION
sigblock, sigmask, sigpause, sigsetmask - block signals sigblock() adds the signals specified in mask to the set of signals currently being blocked from delivery. Signals are blocked if the appropriate bit in mask is a 1; the macro sigmask is provided to construct the mask for a given signum. sigblock() returns the previous mask. The previous mask may be restored using sigsetmask(). sigpause() assigns mask to the set of masked signals and then waits for a signal to arrive; on return the set of masked signals is restored. mask is usually 0 to indicate that no signals are now to be blocked. sigpause() always terminates by being interrupted, returning -1 and setting errno to EINTR. sigsetmask() sets the current signal mask (those signals that are blocked from delivery). Signals are blocked if the corresponding bit in mask is a 1; the macro sigmask is provided to construct the mask for a given signum. In normal usage, a signal is blocked using sigblock(). To begin a critical section, variables modified on the occurrence of the signal are examined to determine that there is no work to be done, and the process pauses awaiting work by using sigpause() with the mask returned by sigblock(). It is not possible to block SIGKILL, SIGSTOP, or SIGCONT, this restriction is silently imposed by the system. RETURN VALUES
sigblock() and sigsetmask() return the previous set of masked signals. sigpause() returns -1 and sets errno to EINTR. SEE ALSO
kill(2), sigaction(2), signal(3UCB), sigvec(3UCB) NOTES
Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system libraries or in multi-thread applications is unsupported. SunOS 5.10 19 Feb 1993 sigblock(3UCB)

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