Question

I am in the process of building interactive front-ends to a
distributed application which to date has been used to run workloads
that had a batch-job like structures and needed no UI at all. The application is mostly written in Perl and C and runs on a mix of Unix and Windows machines, but I think this isn’t relevant to the UI.

The first such frontend is going have a command-line user interface —
currently, I envision something similar to the CLIs of the Procurve
switches and Cisco routers that I have worked with.

Like modern network gear CLIs, commands are going to resemble
simple sentences, (i.e. show vlans ports 1-4) and the CLI will
have some implicit state, much in the way that Unix shells and
cmd.exe in Windows have environment variables and current working
directories. Moreover, I’d like to implement great tab completion that
is aware of the application’s state as much as possible and I want to be able to do that with as
little application-specific code as possible.

The low-level functionality (terminal I/O) seems easy to implement on
top of GNU Readline or similar libraries, but that’s only where the
real fun starts. So far I have looked at the Perl modules
Term::Shell
and
Term::ShellUI,
but I’m not convinced that I want to use either of them. I am still
considering rolling my own solution and at the moment I am primarily looking for
inspiration.

Can you recommend any application or library, regardless of
implementation language, that implements a good CLI from which I can
borrow ideas?

Answer 1

You could try having a look at libcli :

“Libcli provides a shared library for
including a Cisco-like command-line
interface into other software.”

http://code.google.com/p/libcli/

BTW – I forgot to mention that it is GNU Lesser GPL and actually used by Cisco in some products.