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SIG_DFL, SIG_IGN

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SIG_DFLSIG_IGN

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Types

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

Run this code

#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

Run this code

#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

C17 standard (ISO/IEC 9899:2018):

7.14/3 Signal handling <signal.h> (p: 193)

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):

4.7 SIGNAL HANDLING <signal.h>

[edit] See also

C++ documentation for SIG_DFL, SIG_IGN

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