In this section we will see how to write a program in C that cannot be terminated by the Ctrl + C key.
The Ctrl + C generates the keyboard interrupt, and it stops the execution of the current process. Here when we will press the Ctrl + C key, it will print a message then continues the execution. To use this functionality, we will use the signal handling technique in C. When the Ctrl + C is pressed it generates SIGINT signal. There are some other signals and their functionalities in the following list.
| Signal | Description |
|---|---|
| SIGABRT | Indicates Abnormal termination |
| SIGFPE | Indicates floating point exception |
| SIGILL | Indicates invalid instruction. |
| SIGINT | Indicates interactive attention request sent to the program. |
| SIGSEGV | Indicates invalid memory access. |
| SIGTERM | Indicates termination request sent to the program. |
Here we will use the standard C library function signal() to handle these signals.
Example Code
#include <stdio.h>
#include <signal.h>
void sigint_handler(int signum) { //Handler for SIGINT
//Reset handler to catch SIGINT next time.
signal(SIGINT, sigint_handler);
printf("Cannot be stopped using Ctrl+C \n");
fflush(stdout);
}
main () {
signal(SIGINT, sigint_handler);
while(1) { //create infinite loop
}
}Output
Cannot be stopped using Ctrl+C Cannot be stopped using Ctrl+C