Trying to make a signal handler to ignore signals

**PRJ** · 11-14-2019

i wrote a code to handle when CTRL C presses and to ignore CTRL Z signal
i am trying to run a donothing.c file from within my code but it does not run
donothing.c literally is just an infinite loop printing nothing

Trying that to see if after exec it does go back to default handler from parent

here is my code

Code:

#include <signal.h>
#include <stdio.h>
#include <unistd.h>




void sigHandler(int sig)
{
signal(SIGINT, sigHandler);
printf("CTRL C does not work\n");
}
int main(int argc, char *argv[]){ 




int pid; 
pid = fork();






if(pid == 0){
char* args[2] ;
args[0] = "./donothing";
args[1] = 0;
execvp(args[0], args);
//execl("donothing", NULL);


}else if(pid > 0){


signal(SIGINT, sigHandler);
kill(pid, SIGINT);
}

}

**Salem** · 11-14-2019

Nothing happens because you kill the child immediately.

Oh, and your indentation needs work.

Code:

#include <signal.h>
#include <stdio.h>
#include <unistd.h>

void sigHandler(int sig)
{
  signal(SIGINT, sigHandler);
  // don't use printf here
  // see http://man7.org/linux/man-pages/man7/signal-safety.7.html
  printf("CTRL C does not work\n");
}

int main(int argc, char *argv[])
{
  int pid;

  pid = fork();
  if (pid == 0) {
    char *args[2];
    args[0] = "./donothing";
    args[1] = 0;
    execvp(args[0], args);
  } else if (pid > 0) {
    signal(SIGINT, sigHandler);  // useless
    kill(pid, SIGINT);  // immediate infanticide
  }

  return 0;
}

Your signal hander only has scope in this process, but you never invoke it in this process.

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