signal(3C)						   Standard C Library Functions 						signal(3C)

NAME

       signal, sigset, sighold, sigrelse, sigignore, sigpause - simplified signal management for application processes

SYNOPSIS

       #include <signal.h>

       void (*signal(int sig, void (*disp)(int)))(int);

       void (*sigset(int sig, void (*disp)(int)))(int);

       int sighold(int sig);

       int sigrelse(int sig);

       int sigignore(int sig);

       int sigpause(int sig);

DESCRIPTION

       These  functions  provide  simplified signal management for application processes. See signal.h(3HEAD) for an explanation of general signal
       concepts.

       The signal() and sigset() functions modify signal dispositions. The sig argument specifies the signal,  which  may  be  any  signal  except
       SIGKILL	and  SIGSTOP. The disp argument specifies the signal's disposition, which may be SIG_DFL, SIG_IGN, or the address of a signal han-
       dler. If signal() is used, disp is the address of a signal handler, and sig is not  SIGILL, SIGTRAP, or	SIGPWR, the system first sets  the
       signal's  disposition to  SIG_DFL before executing the signal handler. If sigset() is used and disp is the address of a signal handler, the
       system adds sig to the calling process's signal	mask before executing the signal handler; when the  signal  handler  returns,  the  system
       restores  the  calling process's signal mask to its state prior to the delivery of the signal. In addition, if sigset() is used and disp is
       equal to  SIG_HOLD, sig is added to the calling process's signal mask and the signal's disposition remains unchanged.

       The sighold() function adds sig to the calling process's signal mask.

       The sigrelse() function removes sig from the calling process's signal mask.

       The sigignore() function sets the disposition of sig to	SIG_IGN.

       The sigpause() function removes sig from the calling process's signal mask  and suspends the calling process until a signal is received.

RETURN VALUES

       Upon successful completion, signal() returns the signal's previous disposition. Otherwise, it returns  SIG_ERR and sets errno  to  indicate
       the error.

       Upon  successful  completion,  sigset()	returns SIG_HOLD if the signal had been blocked or the signal's previous disposition if it had not
       been blocked. Otherwise, it returns  SIG_ERR and sets errno to indicate the error.

       Upon successful completion, sighold(), sigrelse(), sigignore(), and sigpause(), return  0. Otherwise, they return  -1  and  set	 errno	to
       indicate the error.

ERRORS

       These functions fail if:

       EINTR	 A signal was caught during the execution sigpause().

       EINVAL	 The value of the sig argument is not a valid signal or is equal to  SIGKILL or  SIGSTOP.

USAGE

       The sighold() function used in conjunction with sigrelse() or sigpause() may be used to establish critical regions of code that require the
       delivery of a signal to be temporarily deferred.

       If signal() or sigset() is used to set  SIGCHLD's disposition to a signal handler, SIGCHLD will not be  sent  when  the	calling  process's
       children are stopped or continued.

       If  any of the above functions are used to set SIGCHLD's disposition to SIG_IGN, the calling process's child processes will not create zom-
       bie processes when they terminate (see exit(2)). If the calling process subsequently waits for its children, it blocks  until  all  of  its
       children terminate; it then returns -1 with errno set to ECHILD (see wait(3C) and waitid(2)).

       The  system  guarantees	that if more than one instance of the same signal is generated to a process, at least one signal will be received.
       It does not guarantee the reception of every generated signal.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       exit(2), kill(2), pause(2), sigaction(2), sigsend(2), waitid(2), signal.h(3HEAD), wait(3C), attributes(5), standards(5)

SunOS 5.11							    6 Sep 2007								signal(3C)