12. Ignoring and Restoring Default Signal Handling

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12. Ignoring and Restoring Default Signal Handling

Describe how to ignore a signal in a C program using the signal() function. Additionally, explain how to restore the default action for a signal after setting a custom handler. Provide examples for both scenarios using the SIGINT signal.

gaurav133232

A signal can be ignored by setting the signal handler to SIG_IGN. Ignoring a signal means no action will be taken when the signal is recieved.

For e.g:-

#include <stdio.h>
#include <unistd.h>
#include <signal.h>
void ouch(int sig)
{
   printf("OUCH! - I got signal %d\n", sig);
   (void) signal(SIGINT, SIG_IGN);
}
int main()
{
   (void) signal(SIGINT, ouch);

   while(1)
   {
        printf("Hello World!\n");
        sleep(1);
   }
}
It can be restored to default by defining the handler to SIG_DFL, for e.g:-

#include <stdio.h>
#include <unistd.h>
#include <signal.h>
void ouch(int sig)
{
   printf("OUCH! - I got signal %d\n", sig);
   (void) signal(SIGINT, SIG_DFL);
}
int main()
{
   (void) signal(SIGINT, ouch);

   while(1)
   {
        printf("Hello World!\n");
        sleep(1);
   }
}

12. Ignoring and Restoring Default Signal Handling

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