quoth the Paul Lutus:
darren kirby wrote:
> Hello all,
>
> A script I have written needs the ability to move files. I thought I
> would be clever and use File.rename(old, newdir + new) but this is giving
> me an error: `rename': Invalid cross-device link. I gather this is
> because I am renaming the file to a different partition.
No, it is because you are trying to use "rename" to physically move a file,
and the system is objecting to this misconception. File.rename can only
rename files, it cannot move them. It works only on one storage
device/volume/whatever.
Well, I think that's pretty much what I said. If you 'rename' a file
from /somepath/somefile.txt to /someotherpath/somefile.txt within the same
partition you have effectively 'moved' it haven't you...
> So then I found FileUtils and used:
> require 'fileutils'
> include FileUtils
> mv( old, new)
>
> This is working but seems an overly verbose and convoluted way to move a
> file.
Umm, compared to what? It moves the file using a method named "mv", just
like the Linux/Unix command of the same name.
I am typically very impressed with how much you can do with a little amount of
code in Ruby. For instance, I only had to add one line to add some recursive
directory handling in my script:
From:
files += Dir.glob("*.#{t}")
To:
files += Dir.glob("**/*.#{t}")
Whereas to move a file, a fairly basic operation, I need four lines of code:
require 'fileutils'
include FileUtils
cp(old, new )
rm (old)
I have to change "mv" to "cp" and add the "rm" because the old file is not
automatically removed...
> I had a look at the fileutils.rb source and found this (for 'mv'):
> # Moves file(s) +src+ to +dest+. If +file+ and +dest+ exist on the
> # different disk partition, the file is copied instead
That is what "mv" does. If the new and old filenames and paths allow the
file to remain on the same device, a simple rename is carried out. If not,
the file is copied to the destination and deleted from the source.
Right, I've got that...
> So I guess my real question is: is there a technical reason or some
> arbitrary reason there is no File.move() method that can handle this
> transparently? I would think it would be quite useful...
It might be because not all operating systems on which Ruby can be
installed know the "mv" operation as described above. Just a guess.
I am just wondering because there are (AFAIK) other methods that handle the
operation transparently even though the underlying OS does it differently.
Not trying to troll, I am just curious...
-d
···
--
darren kirby :: Part of the problem since 1976 :: http://badcomputer.org
"...the number of UNIX installations has grown to 10, with more expected..."
- Dennis Ritchie and Ken Thompson, June 1972