Question

I am new to C programming. I am trying to run a program given by the path specified by the user using the fork(), exec(), and waitpid() commands. I have been trying to get this to run correctly for hours now and I keep getting errors I am not sure how to troubleshoot, as soon as I solve one error, new ones arise. I was wondering if someone can help me understand why my implementation does not work smoothly?

Many thanks

#include <stdio.h>
#include <string.h>
#include <stdlib.h>


int main(void)  {
    char command1[256], command2[256], path[556];
    printf("# ");
    scanf("%s", command1);
    scanf("%s", command2);
    scanf("%s", path);
    if(strcmp(command1,"quit")==0)
        exit(0);
    else if(strcmp(command1, "run")==0 && strcmp(command2, "command")==0){

            printf("%s", path);

            pid_t process;

            process = fork();

            //fork error
            if (process < 0){
               perror("fork");
               exit(0);
            }
            else if (process > 0){  //this is the parent process
               execl(path, "sh" , "-c", ":ls -l *.c", 0);
            }
            else {//this is the child process
               waitpid(process); //waits until the program terminates 
            }

    }




return 0;

}

Answer 1

It looks to me like you have things swapped. With fork/exec, you generally do the exec in the child process, and the waitpid in the parent process.