Re: [ECOS] Any shell available?

[Andrew Lunn <andrew at lunn dot ch>]

On Mon, May 29, 2006 at 02:37:01PM +1000, Tang Yi wrote:
> Hi Gary Thomas,
> 
> Thank you for replying me.
> 
> But I don't quite agree with you. Since some of the guys in our group is 
> deeply involved in uclinux and from their point of view, a shell is quite 
> important for embeded linux systems.

eCos != linux

They have very differnet design goals.
 
> And it provide:
> 
> 1. The ability to interact with the system in real-time. This is useful for 
> checking the system status, experimenting, testing, copying files into the 
> system, etc.
> 
> 2. A lot of shells can also be used as a programming language (e.g. bash). 
> The programs are usually quite simple (e.g. deciding what programs to run 
> at system startup), but can also get quite complex.
> 
> Maybe your view is true for the traditional embedded systems, but for some 
> fancy embedded systems nowadays, they do focus a lot on the interface 
> between humans and machines.
> 
> And I found ecos provide an package which support the GUI interface of 
> microwindows, maybe that's a good substite for simple shell. But I wonder 
> whether all the targets support microwindows?

We should probably start by defining what a shell is!

A shell is a way of telling the system to load a program from
secondary storage and execute it. So a DOS Box is a shell, bash is a
shell, the Windows explorer is a shell. Shell scripts are just a
sequence of programs being loaded and executed under the control of a
text file.

Now eCos has no concept of loading a program from secondary storage
and executing it. It has no concept of a program. It has no concept of
a process. Without these concepts a shell is impossible. 

eCos has one application, defined at link time, which does everything
in the system.

What is possible is CLIs and GUIs to allow interaction with the
application.  Microwindows is a library which provides the
infrastructure to build a GUI into the application. It would also be
possible to write a library of functions for implementing CLIs in the
application.

             Andrew             

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