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Date: Mon, 27 Mar 2006 08:12:07 -0500 (EST)
From: Igor Peshansky <pechtcha AT cs DOT nyu DOT edu>
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Subject: Re: Multiple cygwin installs
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On Sun, 26 Mar 2006, Larry Hall (Cygwin) wrote:

> Brian Hawkins wrote:
> > Just FYI.  I found a pretty good way to manage multiple cygwin installs.
> >
> > I use the windows subst command.
> >
> > It works like this.  Create a directory c:\cyginstalls.  Then beneath
> > it create a directory for each cygwin install you want like cygwin1,
> > cygwin2 whatever.  Then use the subst command like so:
> > subst x: c:\cyginstalls\cygwin1
> >
> > Now install cygwin to x:\.  Change the subst to c:\cyginstalls\cygwin2
> > and install again to x:\.
> >
> > To choose what cygwin you use just subst x to the appropriate folder.
> > Kind of a poor mans symbolic link.
>
> Why are you commandeering one thread to inject another?  If you have
> something you want to say and it has nothing to do with any previous
> thread, just start a new one by sending email to the list.

Very true.

> The flaw that I see with your approach is that you're not taking into
> account any existing mounts in the mount table.  Without resetting the
> mount table in between each installation, you will very likely end up
> with subsequent installations overwriting the first one.

Not quite true.  The mounts aren't a problem in this case, since they'll
be pointing to x: (not whatever x: is substed to).  However, you have to
make *very* sure that a) none of these directories are in the PATH, and b)
none of the programs in those directories are invoked explicitly (in
particular, services will be a problem).

> FWIW, if you want something similar to symbolic links for directories
> and you're running W2K or above with NTFS, you can use reparse points.
> See the "junction" utility from www.sysinternal.com if you're interested
> in this.

True, but the same exact issues arise regarding the PATH and running
programs/services.
	Igor
-- 
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