/etc/alternatives was RE: [Re: GCC 4 installation problem]
Thu Mar 26 15:39:00 GMT 2009
Dave Korn wrote:
> Sounds more to me like you forgot to use the alternatives program to
> configure the alternatives and have been messing around manually in
> private data directories and broken it.
> (You're not the first person to do this. For some reason it seems
> be a hard-to-resist temptation for people to just dive into the data
> directories and start tampering, rather than say reading the
> alternatives readme or man/info page which would explain the
> command-line syntax by which alternatives.exe will switch over the
> symlinks correctly.)
I see two problems here:
1) Unless you already know that /etc/alternatives is a 'managed'
directory, there's nothing to suggest that there's any tool associated
with it, and certainly nothing to suggest that there's an associated
2) It's so easy to manually change the links that it's unlikely anyone
is going to spend time looking for some (possibly non-existent) tool to
do it. By the time you've found the right tool, you could have changed
the link and got on with whatever you were trying to do in the first
When the directory first appeared on Linux, I thought the links were
just set up manually. It took me a while to discover that they were
managed, and that was only by digging around in RPMs for post-install
scripts to find out what kept changing my X desktop manager after an
For the first problem, I think it would help avoid installation problems
if the directory contained a simple README file explaining how to
properly maintain the links, and why manually changing them is a bad
idea. To avoid looking like just another link, and thus getting
overlooked, I think this should be a real file, rather than a symlink
to the README in the doc directory. Maybe Chuck could add this to the
cygwin alternatives package, or perhaps he would prefer the upstream
chkconfig maintainer to consider it.
For the second problem, perhaps it would also help if the names of the
links in the alternatives directory were a hash of the program name.
/usr/bin/gs -> /etc/alternatives/9ad6a289eea9c92be09d3a5a8bc737e6
/etc/alternatives/9ad6a289eea9c92be09d3a5a8bc737e6 -> /usr/bin/gs-x11
where 9ad6a289eea9c92be09d3a5a8bc737e6 is the md5sum of "/usr/bin/gs".
This would make it much more obvious that the links were managed, or
at least give one pause for thought before diving in.
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