How a CLI could use the client environment executables files?

Hello all,

I would like to code my own atompub client and server. I use atompub
to expose different hierarchical collections of members.I would like
the client being an interactive command line tool. Additionally to be
used as a feed reader, a consumer of the CLI would probably use it
for: bookmarking a collection; refreshing bookmarked collections;
using diff tools to compare local files and then POSTing the output
content to a collection; etc.

The biggest challenge I face is how the CLI could use the client
environment executables files restfully?

I need to access the diff tools on the client-side system. Does it
fail any constraints the fact that the CLI would try to access the
diff executable tools under the hood? I would provide to the consumer
the hypermedia controls necessary to fill in the arguments that will
be passed to the executables. Just like HTML forms. What about
code-on-demand instead? The client would executes, as an example,
shell scripting fragment depending on the client environment setup
capabilities. Just like the browser executes JavaScript? It has some
advantages that the client could be partly able to update itself.

Otherwise I would need to let the server do the diff which will be
retrieve by the client. But the client and the server will most of the
time be on the same machine or local network. The client needs to
access the file system and do operations on files, which the local web
server could do.

Any advices? Thanks.
-- Philippe