[ILUG] which which

[Colm Buckley]

> My main problem is the 'which' command; if I type 'which which', I'm told
> that it's an internal shell command. However, if I run 'newwhich which'
> (newwhich is a which I took from a different, secure box), it gives me
> '/usr/bin/which'.

Panic ye not.  'which' is frequently built-in to shells for speed - the
shell version will always tell you exactly what it's going to execute.
In the case of 'which' itself, this is obviously the shell built-in, as
they get executed in preference to executables in the PATH.

Your 'newwhich' command presumably works by looking in $PATH for an
executable of the given name.  It can't know about shell builtins, so
it'll return the one it finds in /usr/bin.  You'll probably find that
'/usr/bin/which which' will return '/usr/bin/which', too.

In short, your shell has a built-in 'which', which is what gets executed
when you run plain 'which'.  There's also an executable 'which' (in
/usr/bin), which only parses $PATH looking for executables, and can't
know about the shell built-ins.

        Colm

-- 
Colm Buckley BA BF | NewWorld Commerce, 44 Westland Row, Dublin 2, Ireland
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