[Rd] Question about Unix file paths

Prof Brian Ripley ripley at stats.ox.ac.uk
Tue Nov 25 08:35:57 MET 2003

On Mon, 24 Nov 2003, Duncan Murdoch wrote:

> >Duncan Murdoch <dmurdoch at pair.com> writes:
> >
> >> Gabor Grothendieck pointed out a bug to me in list.files(...,
> >> full.name=TRUE), that essentially comes down to the fact that in
> >> Windows it's not always valid to add a path separator (slash or
> >> backslash) between a path specifier and a filename.  For example,
> >> 
> >> c:foo
> >> 
> >> is different from
> >> 
> >> c:\foo
> >> 
> >> and there are other examples.
> I've committed a change to r-patched to fix this in Windows only.
> Sounds like it's not an issue elsewhere.

I think there are some potential issues with doubling separators and final
separators on dirs.  On Unix file systems /part1//part2 and /path/to/dir/
are valid.  However, file systems on Unix may not be Unix file systems:
examples are earlier MacOS systems on MacOS X and mounted Windows and 
Novell systems on Linux.  I would not want to assume that all of these
combinations worked.

> Gabor also suggested an option to use shell globbing instead of
> regular expressions to select the files in the list, e.g.
> list.files(dir="/", pattern="a*.dat", glob=T)
> This would be easy to do in Windows, but from the little I know about
> Unix programming, would not be so easy there, so I haven't done
> anything about it.

It would be shell-dependent and OS-dependent as well as a retrograde step,
as those who wanted to use regular expressions no longer would be able to.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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