echo $$
do_fork()
echo $$

<ProcessA PID>
<ProcessB PID>
<ProcessA PID>

<ProcessA PID>
<ProcessA PID>
<ProcessB PID>

echo child & echo parent

first(); fork(); second(); third();

after_fork () { second; third; }
first; after_fork & after_fork

first(); if (fork()) parent(); else child();

#!/bin/bash

(sleep 2; echo "subsh 1")&
echo "topsh"