#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
int main(int argc, char *argv[])
{
    FILE *f;
    if ((f = popen("cut -f2 -d ' '", "w")) != -1)
    {
        fprintf(f, "%s", "vv aaa");
        pclose(f);
    }
}