Namespaces
Variants
Views
Actions

SIG_DFL, SIG_IGN

From cppreference.com
< c‎ | program
Defined in header <signal.h>
#define SIG_DFL /*implementation defined*/
#define SIG_IGN /*implementation defined*/

The SIG_DFL and 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.

Constant Explanation
SIG_DFL default signal handling
SIG_IGN signal is ignored

Contents

[edit] Example

#include <signal.h>
#include <stdio.h>
 
int main(void)
{
    /* using the default signal handler */
    raise(SIGTERM);
    printf("Exit main()\n");   /* never reached */
}

Output:

(none)

[edit] Example

#include <signal.h>
#include <stdio.h>
 
int main(void)
{
    /* ignoring the signal */
    signal(SIGTERM, SIG_IGN);
    raise(SIGTERM);
    printf("Exit main()\n");
}

Output:

Exit main()

[edit] References

  • C11 standard (ISO/IEC 9899:2011):
  • 7.14/3 Signal handling <signal.h> (p: 265)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.14/3 Signal handling <signal.h> (p: 246)
  • C89/C90 standard (ISO/IEC 9899:1990):

[edit] See also

C++ documentation for SIG_DFL, SIG_IGN