[GRASS-user] How to install Grass into Ubuntu

[Glynn Clements]

Matt B wrote:

> > Note that GRASS won't let you select a mapset as the current mapset
> > (where new files are stored) unless you own it. Write permission isn't
> > sufficient.
> >
> > If you are creating a location which is to be shared by multiple
> > users, you either need to create a mapset directory for each user,
> > owned by the user, or grant all such users write permission on the
> > location directory so that they can create their own mapset directory
> > (which they will own).
> 
> Thanks for the heads up on this Glynn, my problem is that I'm on a dual boot
> system and I'm storing mapsets/data on an NTFS drive. It's being
> automatically mounted with the owner set as root and read/write permission
> for everyone. If I put the data on the ext3 filesystem, it works. I'll mess
> around with fstab and mount the data drive as the appropriate user. Having
> said that.... it does seem to me that this sort of check is doubling up.
> File permissions are usually run by the file system/OS. While having a
> sanity check for "read/write" access is a good idea, checking for ownership
> seems a little over the top. <insert newby user disclaimer here>.

AFAICT, the check exists because otherwise people grant group-write
permission to mapset directories without fully understanding the
consequences. In particular, you can end up being unable to modify,
rename or remove files because they reside in a directory created by
another user and lacking group-write permission.

The possibility of "free-for-all" filesystems (i.e. where not only are
all files and directories world-writable, but where any new files and
directories will always be world-writable) has only arisen recently.

The native Windows builds skip the ownership check, but Unix builds
will perform it regardless of the filesystem type. Unfortunately, I
don't know of any (robust and portable) way to detect when a Windows
filesystem is being used on Unix.

-- 
Glynn Clements <glynn at gclements.plus.com>