#!/bin/bash

# Fibonacci numbers
# Writes an infinite series to stdout, one entry per line
function fib() {
  local a=1
  local b=1
  while true ; do
    echo $a
    local tmp=$a
    a=$(( $a + $b ))
    b=$tmp
  done
}

# output the 10th element of the series and halt
fib | head -10 | tail -1