progressbar.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <time.h>

int main(void) {
  srand(time(NULL));
  const int N = 50;

  for (;;) {
    int n = rand() % N;
    int i;
    fputs("\rprogress bar [", stdout);
    for (i = 0; i < n; i++) {
      putchar('#');
    }
    for (i = n; i < N; i++) {
      putchar(' ');
    }
    putchar(']');
    usleep(10000);
  }
  return 0;
}