Question

Write a C program that creates (or spawns) a child process to execute the Unix's command (echo) with a string as the command-line argument; while the program itself (the parent process) will execute another Unix command less with a filename as the command-line argument. If you aren't sure how the echo and less commands are meant to behave, experiment with them by running them directly from the command line first.

Answer 1

Hi,

Please go through code and output.

CODE:

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

int main(int argc, char ** argv)
{
   if(argc < 3) // check arguments
   {
       printf("Usage: ./a.out string filename\n");
       return 0;
   }
   if(fork() == 0) // create child process
   {
       // child
       char str[64] = {0};
       sprintf(str, "echo %s", argv[1]); // copy command in str
       system(str); // exicute command
   }
   else
   {
       // parent
       char str[64] = {0};
       sprintf(str,"less %s",argv[2]); // copy command in str
       system(str); // exicute command
   }
}

OUTPUT: