Types, shells, echoes and other phenomena ? [ was: Re: dapper sudo ]

[Erik Christiansen]

On Wed, Jul 05, 2006 at 08:21:58PM +1000, Peter Garrett wrote:

> So... I'm more confused than I was now :) Are there two "echoes" ? ( An
> echo of an echo perhaps ? 
> 
> Echo...echo...echo...echo.... ( fading out as it bouces between the
> mountains..... )

Peter,

I suspect that you suspect that the echoes are illusory, and you're
right. In fact, it's just a case of which which is which:

$ which which
which is aliased to `type'     # In my .bashrc for the last decade or
                               # two, 'cos some unices lacked which.

$ unalias which
$ which which
/bin/which                     # Oooh!, there is one in ubuntu.

But /bin/which merely locates the first occurrence of the command in
$PATH, which is not the whole story in a bash shell. type gives a more
'truthful' answer. (I begin to like my alias more, by the minute. :-)

As an aside, I suppose that for the OP, it is moot which echo is which,
because /bin/echo also outputs a trailing newline if -n is not
specified, so neither would inherently substitute for /dev/null.

:-)

Erik