Remind me to implement bb_fork_exec()...
diff --git a/docs/busybox.net/programming.html b/docs/busybox.net/programming.html
index f77f3c3..6dbe693 100644
--- a/docs/busybox.net/programming.html
+++ b/docs/busybox.net/programming.html
@@ -235,6 +235,12 @@
<h2><a name="tips_vfork">Fork and vfork</a></h2>
+<p>Busybox hides the difference between fork() and vfork() in
+libbb/bb_fork_exec.c. If you ever want to fork and exec, use bb_fork_exec()
+(which returns a pid and takes the same arguments as execve(), although in
+this case envp can be NULL) and don't worry about it. This description is
+here in case you want to know why that does what it does.</p>
+
<p>On systems that haven't got a Memory Management Unit, fork() is unreasonably
expensive to implement, so a less capable function called vfork() is used
instead.</p>
@@ -277,6 +283,11 @@
sharing the same memory without stomping all over each other. As soon as
the child calls exec(), the parent resumes.</p>
+<p>If the child's attempt to call exec() fails, the child should call _exit()
+rather than a normal exit(). This avoids any atexit() code that might confuse
+the parent. (The parent should never call _exit(), only a vforked child that
+failed to exec.)</p>
+
<p>(Now in theory, a nommu system could just copy the _stack_ when it forks
(which presumably is much shorter than the heap), and leave the heap shared.
In practice, you've just wound up in a multi-threaded situation and you can't