backquotes, system, shell and ruby

Somebody suggested I use zsh instead of bash for my commandline, so I
looked at it, looked at the syntax for tweaking the profile files, and
said...
"Yuck! Another badly designed syntax! Why can't I just use Ruby?"

And that got me thinking.

Consider backquotes.

a = `wc *.c`

What did that do? Same as open("|wc *.c").

It ran bash!

Yuck!

system( "tar -xvzf foo.tgz foo")

What did that do? It ran shell!

Why? Why does a scripting language like Ruby keep invoking an old and bad
scripting language call shell?

Because...

 a) Ruby doesn't have a good syntax for invoking and dealing with
    processes and pipes between processes.

 b) Ruby doesn't have a built in understanding of ENV['PATH']

 c) Ruby doesn't have such a simple syntax for globbing (beyond
    Dir['*.c'])

    Consider the "rename" facility that comes with perl these days.
       For example, to rename all files matching "*.bak" to strip the exten-
       sion, you might say

               rename 's/\.bak$//' *.bak

       To translate uppercase names to lower, you'd use

               rename 'y/A-Z/a-z/' *

   Ooh! Looky! Nice! Wouldn't it be nice to have the power of ruby
   intertwingled with the commandline.


Ruby does have Shell.rb, which takes us halfway there. (If it had
decent docs...)

How hard would it be to extend the backtick syntax to be a pure ruby
thing. ie. So proc_exec doesn't invoke bash, but invokes Shell.rb?


Hmm. Could we even do this entirely in UserLand? ie. Couldn't we
override proc_exec and replace it with ruby code that parses the
string, handles the redirects, variable interpolation quoting and
forks, then just directly execs the program without ever touching sh?


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