SIG_ERR

 

C

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Program support utilities

Program termination
abort exit quick_exit (C11) _Exit (C99)	atexit at_quick_exit (C11) EXIT_SUCCESSEXIT_FAILURE
Unreachable control flow
unreachable (C23)
Communicating with the environment
getenvgetenv_s (C11)	system
Memory alignment query
memalignment (C23)
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signal raise sig_atomic_t	SIG_DFLSIG_IGN SIG_ERR
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SIGABRTSIGFPESIGILL	SIGINTSIGSEGVSIGTERM
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setjmp	longjmp
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jmp_buf

 

Defined in header <signal.h>
#define SIG_ERR /* implementation defined */

A value of type void (*)(int). When returned by signal, indicates that an error has occurred.

Example

Run this code

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
 
void signal_handler(int sig)
{
    printf("Received signal: %d\n", sig);
}
 
int main(void)
{
    /* Install a signal handler. */
    if (signal(SIGTERM, signal_handler) == SIG_ERR)
    {
        printf("Error while installing a signal handler.\n");
        exit(EXIT_FAILURE);
    }
 
    printf("Sending signal: %d\n", SIGTERM);
    if (raise(SIGTERM) != 0)
    {
        printf("Error while raising the SIGTERM signal.\n");
        exit(EXIT_FAILURE);
    }
 
    printf("Exit main()\n");
    return EXIT_SUCCESS;
}

Output:

Sending signal: 15
Received signal: 15
Exit main()

References

• C17 standard (ISO/IEC 9899:2018):

• 7.14/3 Signal handling <signal.h> (p: 194)

• 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>

See also

signal	sets a signal handler for particular signal (function)
C++ documentation for SIG_ERR