which/type & built-ins

[Robert J. Reschly Jr.]

      Richard,
You say:
> Does anyone know why the C shell command "which" (ok, /usr/ucb/which)
> and the Bourne shell command "type" don't understand built-in commands?

   The "which" command is an independent program (actually a C-shell
script) which can be called from any command interpreter.  Since the
various command interpreters offer differing sets of built-in commands,
"which" cannot presume to know anything about built-in commands.
Additionally there is no reasonable way for "which" to learn this
information.

> I don't quite see why; surely it would be easy for /usr/ucb/which to
> execute an appropriate switch() after everything else has failed.

   Resulting in "which blurfle" responding with "blurfle is a shell
built-in"?  What action would you have the switch() branch take?  Note
that another failure mode for "which" involves using a shell other than
/bin/csh while having a .cshrc in your home directory.  If this .cshrc
defines any aliases, "which" will gladly report them even though they are
probably inappropriate.

   As for "type", I have no good answers.  Given that "type type"
reports itself as a shell built-in it should be able to report on other
built-ins. My current shell of choice, "tcsh" handles this operation
correctly.

				Later,
				    Bob 
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          Systems Engineering and Concepts Analysis Division
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