Is there a need for Shell script debugger?

[Ron Natalie]

Frankly I doubt that there is much need for a "shell script" debugger.
Unlike C programs, shell is interpretted and the shell already provides
you some nice features (-x -v flags) to watch it's progress.  The only
debug features I can think of as actually being useful you couldn't
implement as either a script or a C program, but would actually need
to take place as a modification to the Shell itself.  These features
would be things like the ability to single step through the script,
examining or setting variables as neccessary between the steps.

-Ron