Menu-spec update (Was: [Patch] Update 'How to' to clarify computation of datadir)

[Joerg Barfurth]

Jeremy White wrote:

> I'm the sysadmin for a network of computers; I've built them
> to all have a common nfs mount point at /mnt/shared;
> all systems have an XDG_DATA_DIRS of something like
> /mnt/shared:/usr/local:/usr.
> 
> I want to install a new package, I type:
>   XDG_DATA_DIRS=/mnt/shared ./install-some-software.sh
> and my software menus are automatically installed into a
> shared location.  Sweet!
> 

For install, you should typically be able to use something like

   ./install-some-software.sh --prefix=/mnt/shared

(or PREFIX=/mnt/shared ./install-some-software.sh, if you prefer).

XDG_DATA_DIRS is a list of pathes - as such it is a bad place to specify 
a uniquer directory (the one to install to). With your default 
XDG_DATA_DIRS, what should that installer do? Silently fall back to 
installing into /usr/local, if /mnt/shared is mounted readonly? What if 
the NFS server for /mnt/shared is down?

> Or maybe I don't want a particular package to be visible to
> users in a particular group; I want to do:
>   XDG_DATA_DIRS=/opt/secret_software ./install-some-software.sh
> 

Having software packages that support installing into a specific prefix 
is fine. And to support your flexibility, the software really should 
install only into the given prefix. Then it is your choice to include 
/opt/secret_software/share into XDG_DATA_DIRS for your users or not.

XDG_DATA_DIRS is a directive for reading (and coalescing) multiple 
source locations. But that should not be mixed with install-prefix 
directives, which always should unambiguously name a single directory. 
So whatever mechanism an installer uses to identify the prefix to 
install to, it should *not* be XDG_DATA_DIRS.

- Joerg

-- 
Joerg Barfurth              Sun Microsystems - Desktop - Hamburg
 >>>>>>>>>>>>>>>>>> using std::disclaimer <<<<<<<<<<<<<<<<<<<<<<<
Software Engineer                         joerg.barfurth at sun.com
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