[Coco] Major OS-9 discovery to enhance script file use.

[Robert Gault]

You have found something there. I just ran procs before and after using 
a ()</1 command and two extra shells were generated.

tim lindner wrote:


> Robert Gault <robert.gault at worldnet.att.net> wrote:

> 

> 

>>(chd /h0/MVUE)</1

> 

> 

> I tested something like this on stock OS9 Level 2. I modified the

> startup file to have this at the end:

> 

> (chd sys) </1

> echo Success!

> 

> After it was done I got my prompt and did a PWD, and found my current

> directory really was /DD/SYS. But the echo command did not execute.

> 

> When shell runs the startup file (or any script) it forks a sub shell,

> changing directories in that sub-shell will not effect the parent shell.

> Period.

> 

> What you have found is a way to crash the sub shell, and exeucte the CHD

> command in the parent shells process. I think it crashes becuase you are

> trying to redirect the STDIN of a built in shell command.

> 

> 

>>(display 1b 21)</1

> 

>  

> This works becuase you dup STDOUT and assign it to STDIN. This works

> around a bug in Select when STDIN is an RBF path. Note, this does not

> crash the sub-shell.

>