C <signal.h> - SIG_DFL, SIG_IGN
The C <signal.h> SIG_DFL, SIG_IGN macros expand into integral expressions that are not equal to an address of any function. The macros define signal handling strategies for signal() function.
| Macros | Description |
|---|---|
| SIG_DFL | (Default handling) The signal is handled by the default action for that particular signal. |
| SIG_IGN | (Ignore signal) The signal is ignored and the code execution will continue even if not meaningful. |
Definition in the <signal.h> header file is:
#define SIG_DFL /* implementation defined */ #define SIG_IGN /* implementation defined */
Example:
The example below shows how a signal is handled by default.
#include <signal.h>
#include <stdio.h>
int main(void) {
//using the default signal handler
raise(SIGTERM);
//this will never be reached
printf("Exit main()\n");
return 0;
}
The output of the above code will be:
Terminated
Example:
The example below shows how to use SIG_IGN macro function to ignore a signal.
#include <signal.h>
#include <stdio.h>
int main(void) {
//ignoring the signal
signal(SIGTERM, SIG_IGN);
raise(SIGTERM);
printf("Exit main()\n");
return 0;
}
The output of the above code will be:
Exit main()
❮ C <signal.h> Library
