Didier Kryn writes:

>     Did you try it? The documentation of Bash is not clear. I 
> think it says that a bash script can only wait the processes it 
> has launched. Does it mean it maintains a list of them, or is it 
> just the consequence of the fact that any process but pid1 
> cannot adopt others' children? In the last case, why the need to 
> repeat it.

Processes cannot adopt children; the kernel foists processes on pid 1
without asking either pid 1 or any other process.

Bash's source code is very, very large compared to zsh, which offers
roughly the same functionality. The extra lines of code code have to do
something, so it's entirely possible that bash tries to duplicate the
kernel's list of children. Or not. I'm not going to look, it doesn't seem a
useful thing to do.

Arnt