Question

Can someone help this simple program to prompt the users for a command?

#include "unistd.h"
#include "stdio.h"


 int main(){
      char command[80];
      while (putchar('#'), gets(command)) {
        if (fork()){
          wait(0); /* Parent */
    }
        else { /* Child */
          execlp(command, command, 0);
          printf("command not found\n");
          exit(1);
        }
      }

}

Command given: gcc system.c -o system.exe

Error as followed:

system.c: In function ‘main’:

system.c:12:7: warning: missing sentinel in function call [-Wformat]

system.c:14:7: warning: incompatible implicit declaration of built-in function ‘exit’ [enabled by default]

Answer 1

Have you tried including unistd.h & stdio.h ?

Oh and by the way, from the manual of gets() :

Never  use gets().  Because it is impossible to tell without knowing the data in advance how many characters gets() will read, and because
gets() will continue to store characters past the end of the buffer, it is extremely dangerous to use.  It has been used to break computer
security.  Use fgets() instead.