How to synchronize multiple computers via usb stick?

Question

I have three computers on which I work most of the time and I have some files, that I have to access/change on all three and thus I have to sync these files.  I would like to do this using an usb stick.  To do so, I formatted a partition on my usb stick as ext4 (without journaling) and then use unison to synchronize the files from one computer to the usb stick when I'm done working on one computer and before I start, I do the same.
Unfortunately, I have different uid and gid on the different computers (and I cannot change that as I'm not admin on every one).  Unison can still take readable files from the usb stick and store them with my `correct' local uid, but unfortunately it cannot create new files/folders on the usb stick, as the folders are often with rwxr-xr-x permission.
There are some suggestions, such as here to simply change the ownership of all files recursively, but since I'm not root, I cannot do that.  (Additionally this solution does not feel optimal, as I would have to change the permission bits with every mount -- and this is probably not the best to do to an usb stick(?).)
So after the whole lament my actual questions:
  o Is there a file system, that can store permissions (such as redable/writable with user and group support), but that I can mount with changed permissions (e.g. translate uid=1023 to uid=17011 while mounting but leavin the actual bits set) and that is suitable for use with an usb stick?
  o Is there a tool to mount/remount the usb stick with `translated' permissions?
  o Is there any other solution you could think of to accomplish my syncing?  (Keep in mind, that sky/cloud drives are no possibilities, as not all of my computers have internet access.)
Note:  The permissions (which file is rwx and which is only r--) is actually something I want to preserve during this sync-process -- that's why I used ext4 in the first place.
Last edited by skunk_junior (2013-05-31 12:40:12)

Answer 1

Trilby wrote:I'm confused, you say you want to preserve the permissions, but you also say you want to change them all to readble.
I don't want to change the permissions stored on the usb stick.  I just want identical files on all my three systems (also with the permissions set correctly), but I want to use my local uid instead of the uid stored on the stick.  So that the mounting system does not see ``uid=1023 has rwx for file /mnt/foo'', as it's stored on the usb stick, but I want it to see ``uid=17011 has rwx for file /mnt/foo''.
I Imagine some tool like a table that links the actual, stored, uid on the stick (1023) to the one, I want my system to perceive (17011).
If I make a file executable, I want to keep that information.  If I store that file on a fat, it's lost.
Last edited by skunk_junior (2013-05-31 13:08:40)