Question

the macro WIFEXITED returned true what does this imply

Answer 1

In the context of programming, specifically when using the C programming language, the macro `WIFEXITED` is typically used in conjunction with the `waitpid` or `wait` system calls to determine the exit status of a child process. When `WIFEXITED` returns true, it implies that the child process has terminated normally by calling the `exit()` system call or by returning from the `main()` function.

The `WIFEXITED` macro is used to check the termination status of a child process and is often used in combination with other macros such as `WEXITSTATUS` to retrieve the exit status value. By evaluating `WIFEXITED` as true, it indicates that the child process has ended without encountering any abnormal conditions or errors. The `WEXITSTATUS` macro can then be used to retrieve the exit status value if needed.

Here's a simple example to illustrate its usage:

#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>

int main() {
    pid_t pid = fork();

    if (pid == 0) {
        // Child process
        printf("Child process executing.\n");
        exit(0);  // Terminate child process normally
    } else if (pid > 0) {
        // Parent process
        wait(NULL);

        if (WIFEXITED(pid)) {
            printf("Child process terminated normally.\n");
            int exitStatus = WEXITSTATUS(pid);
            printf("Exit status: %d\n", exitStatus);
        }
    } else {
        // Fork failed
        fprintf(stderr, "Fork failed.\n");
        return 1;
    }

    return 0;
}

In this example, the parent process waits for the child process to terminate using the `wait` system call. If `WIFEXITED` returns true, it indicates that the child process has terminated normally. The exit status of the child process can be retrieved using `WEXITSTATUS` and then printed out.