error: ‘SIGKILL’ undeclared (first use in this function)

Question

Alright, I was trying to make a simple function to constantly change its PID, but I get this:

error: ‘SIGKILL’ undeclared (first use in this function)

here is my code:

#include <stdio.h>

int changePID(void) {
        int pid = fork();
        printf(pid);
        sleep(3);
        kill(pid, SIGKILL);
}

    int main(void) {
        while (1) {
            changePID();
            }
}

This also may help, http://stackoverflow.com/questions/6501522/how-to-kill-a-child-process-by-the-parent-process — D4zk1tty, Jul 04 '13 at 08:01

Alexis · Accepted Answer · 2013-07-04T08:19:03.663

6

you are missing the line #include <signal.h> for the SIGKILL

printf(pid); is not going to work since printf need a char* and you give him a pid_t

What's the point of killing a child in a loop ?

printf is going to segv in the father so you will never reach kill

and in the son you are going to kill

every process in the process group of the current process with a pid of 0

edited Jul 04 '13 at 08:19

answered Jul 04 '13 at 08:08

Alexis

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`pid_t`comes implicitly with `@include`ing `` which prototypes `fork()` and `sleep()`. – alk Jul 04 '13 at 08:16
doesn't work on windows. I had to hardcode 9 – joseph lake Jun 13 '23 at 05:07

score 2 · Answer 2 · answered Jul 04 '13 at 08:06

2

You need to add:

#include <sys/types.h>
#include <signal.h>

Look at the man page when you have an issue with a system call.

answered Jul 04 '13 at 08:06

Benoit Thiery

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Working now, although I had to fix a few other errors it is fine, thanks! – D4zk1tty Jul 04 '13 at 08:10
Why include ``? – alk Jul 04 '13 at 08:17
+1 for talking about the manpage. It seems that nobody looks at the manpages anymore in 2013... – Matthieu Rouget Jul 04 '13 at 08:45

score 0 · Answer 3 · answered Jul 04 '13 at 08:08

0

try to include

#define <sys/signal.h>

answered Jul 04 '13 at 08:08

Chirag Desai

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error: ‘SIGKILL’ undeclared (first use in this function)

3 Answers3