21sh/myredir/myredir.c


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#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/wait.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
    if (argc < 3)
    {
        fprintf(stderr, "Missing argument\n");
        return 2;
    }
    // Save stdout
    int stdout_dup = dup(STDOUT_FILENO);

    int file_fd = open(argv[1], O_CREAT | O_WRONLY, 0644);

    // Redirect stdout to the file
    dup2(file_fd, STDOUT_FILENO);

    int status;

    pid_t pid = fork();
    if (pid == 0)
    {
        execvp(argv[2], argv + 2);
        return 127;
    }
    else
    {
        waitpid(pid, &status, 0);
        if (WIFEXITED(status))
        {
            status = WEXITSTATUS(status);
            fflush(stdout);
            dup2(stdout_dup, STDOUT_FILENO);
            close(stdout_dup);
        }
        if (status != 127)
            printf("%s exited with %d!\n", argv[2], status);
        else
            fprintf(stderr, "Missing command\n");
        return status == 127;
    }
}