Registering a Common Handler on More Linux Programming

Instead of registering a separate handler for each signal we may decide to handle all signals using a common signal handler. This is shown in the following program:

# include <unistd.h>
# include <sys/types.h>
# include <signal.h>
void sighandler ( int signum )
{
switch ( signum )
{
case SIGINT :

printf ( "SIGINT Received\n" ) ;
break ;
case SIGTERM :
printf ( "SIGTERM Received\n" ) ;
break ;
case SIGCONT :
printf ( "SIGCONT Received\n" ) ;
break ;
}
}
int main( )
{
signal ( SIGINT, sighandler ) ;
signal ( SIGTERM, sighandler ) ;
signal ( SIGCONT, sighandler ) ;
while ( 1 )
printf ( "\rProgram running" ) ;
return 0 ;
}

In this program during each call to the signal( ) function we have specified the address of a common signal handler named sighandler( ). Thus the same signal handler function would get called when one of the three signals are received. This does not lead to a problem since the sighandler( ) we can figure out inside the signal ID using the first parameter of the function. In our program we have made use of the switch-case construct to print a different message for each of the three signals.

Note that we can easily afford to mix the two methods of registeringsignals in a program. That is, we can register separate signal handlers for some of the signals and a common handler for some other signals. Registering a common handler makes sense if we want to react to different signals in exactly the same way