SIGNAL(3F)																SIGNAL(3F)

NAME

       signal - change the action for a signal

SYNOPSIS

       integer function signal(signum, proc, flag)
       integer signum, flag
       external proc

DESCRIPTION

       When  a	process  incurs  a  signal  (see signal(3C)) the default action is usually to clean up and abort.  The user may choose to write an
       alternative signal handling routine.  A call to signal is the way this alternate action is specified to the system.

       Signum is the signal number (see signal(3C)).  If flag is negative, then proc must be the name of the user  signal  handling  routine.	If
       flag  is zero or positive, then proc is ignored and the value of flag is passed to the system as the signal action definition.  In particu-
       lar, this is how previously saved signal actions can be restored.  Two possible values for flag have specific meanings: 0  means  "use  the
       default action" (See NOTES below), 1 means "ignore this signal".

       A  positive  returned  value  is  the previous action definition.  A value greater than 1 is the address of a routine that was to have been
       called on occurrence of the given signal.  The returned value can be used in subsequent calls to signal in  order  to  restore  a  previous
       action definition.  A negative returned value is the negation of a system error code.  (See perror(3F))

FILES

       /usr/lib/libU77.a

SEE ALSO

       signal(3C), kill(3F), kill(1)

NOTES

       f77  arranges  to  trap	certain signals when a process is started.  The only way to restore the default f77 action is to save the returned
       value from the first call to signal.

       If the user signal handler is called, it will be passed the signal number as an integer argument.

4.2 Berkeley Distribution					   May 15, 1985 							SIGNAL(3F)