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Re: man dangling symlink question



* Monique Y. Herman (spam@bounceswoosh.org) [031009 15:32]:
> On Thu, 09 Oct 2003 at 20:30 GMT, David Z Maze penned:
> > "Monique Y. Herman" <spam@bounceswoosh.org> writes:
> > 
> >> I'd never heard of update-alternatives or /etc/alternatives until a
> >> few days ago on this list, and to be honest I'm still a little (a
> >> lot) foggy on what exactly it's used for.  For instance, I have
> >> /etc/alternatives/vi and /etc/alternatives/editor ... what
> >> applications will use these values?
> > 
> > nvi, vim, and elvis (all vi clones) will register alternatives for vi;
> > these, plus emacs, xemacs, nano, etc. will be alternatives for editor.
> > 
> 
> Yes, I understand that.  What I don't understand is, what uses these
> registries?  Does the system set $EDITOR to /etc/alternatives/editor
> under the cover?  Will typing "kedit" suddenly get me vim?  What apps
> respect alternatives instead of, say, $EDITOR or $PAGER, and how do I
> find this out?  Or is this just a convenience that I can choose to use
> when setting up my own users?

No, I think you're imagining it to be far more complicated than it is.

wingnut:~$ type vi
vi is /usr/bin/vi
wingnut:~$ \ls -o /usr/bin/vi
lrwxrwxrwx    1 root           20 2003-04-23 09:25 /usr/bin/vi -> /etc/alternatives/vi
wingnut:~$ \ls -o /etc/alternatives/vi
lrwxrwxrwx    1 root           12 2003-05-28 15:42 /etc/alternatives/vi -> /usr/bin/vim
wingnut:~$ \ls -o /usr/bin/vim
-rwxr-xr-x    1 root      1151736 2003-02-08 12:53 /usr/bin/vim

So when I type 'vi', I get vim, via some symlinks.  That's all.  Any
program that tries to invoke /usr/bin/editor will get vim:

wingnut:~$ \ls -o /usr/bin/editor
lrwxrwxrwx    1 root           24 2003-04-23 09:25 /usr/bin/editor -> /etc/alternatives/editor
wingnut:~$ \ls -o /etc/alternatives/editor
lrwxrwxrwx    1 root           12 2003-09-21 01:43 /etc/alternatives/editor -> /usr/bin/vim
wingnut:~$ \ls -o /usr/bin/vim
-rwxr-xr-x    1 root      1151736 2003-02-08 12:53 /usr/bin/vim


I don't know if kedit does some funky stuff (I've never used it), but I
imagine it is an editor in its own right, and that there are no
alternatives for kedit (/usr/bin/kedit is not a symlink to something in
/etc/alternatives; it is a binary -- unless my assumptions are wrong,
since I've never used kedit).

> (Also seems weird to me that a bunch of pointers to executables would be
> stored in /etc, but maybe that's just me.)

They are part of the configuration of the system.  My having an
/etc/alternatives/editor that points at vim is a representation of a
preference for vim.  It's just one step lighter than having
/usr/bin/editor be a wrapper script that executes vim.  So /etc is a
good place for it, since it is configuration.

good times,
Vineet
-- 
http://www.doorstop.net/
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