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Hardlinks in dropbox folder

Now that Dropbox has stopped supporting symlinks within Dropbox folder (to folders outside Dropbox), my setup no longer works. I wonder if hard links from within Dropbox to folders outside Dropbox would work, meaning that they would sync. Or would Dropbox ignore the external folder?

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Здравко

Hi @mtozsu,

You are welcome.

Just to note: In "very system dependent" I don't mean OS! First of all to be able you must have corresponding permissions. Regular user don't have. Next, as I already noted, hard link and soft link are very different things. Soft link is on top level of your entire file system structure, so can point to, almost, everywhere and there are no too much additional requirements. Hard link is, in fact, change in the FS, so corresponding support have to be! In this context such a "link"s could "point" to FS entries inside particular partition, link from inside don't know anything about other places (drives/partitions and so on). Typically any abstraction layer above the native FS make hard linking imposible. And many other details could have some effect, so very important is the entire setup details. Generally hard linking is not best solution. You can try directory binding or 'opposite sym link' (actual directory inside, pointer outside).

Hope this helps.

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Здравко

Hi @mtozsu,

@mtozsu wrote:
... Or would Dropbox ignore the external folder?

What you mean "ignore the external folder"? Can you define which one is external and which one internal? Hard link and soft link are very different things! "Link" in "hard link" is mostly metaphor.

mtozsu

I have a folder in my ~/Documents folder -- let us call it Papers (so ~/Documents/Papers). Now I create a hard link to it in my Dropbox folder so it is ~/Dropbox/Papers. Now I go and add a file to (or edit a file in) ~/Documents/Papers -- will Dropbox recognize the hard link and sync the changes? It no longer does this with symlinks; the question is whether it would do it with hardlinks...

Здравко

Hi @mtozsu,

If you can create hard link to a folder, could be expected that it will work. BUT, typically you can't! This is very system dependent and usually disabled.

Hope this cast some light.

mtozsu

Noted, thank you.

I should have checked whether I could create a hardlink first -- it turns out I cannot on a Mac.

Здравко

Hi @mtozsu,

You are welcome.

Hope this helps.

auspugs

suggestion, why dont you store everything in the dropbox folder, and then symbolic link from the location you want back to the DropBox folder?

That way the user experience doesnt change, it also is a good visual check on what you have backed up, because from windows explorer you will be able to see that each folder is a symbolic link and therefore the data is backed up automatiacally.

It is just a small change in setup, and you can have your data on a differnt hard drive.

If you use hard links, it must be on the same hard drive.

auspugs

Both Windows and *nix (Linux and Unix) supprot hard links. In windows just go to powershell and install the module, you can hard link folders/directories easily. The main requirement in windows is, that both the hardlink and the folder, is on the same hard drive. Otherwise you need to use a Symbolic link. However I have given the easiest solution below. This change by Dropbox does not effect anything, other than how you set it up. On the flip side, it adds secuirty and solves a lot of issues, because symbolic links are not easy to deal with in programming.

Well done to drop box for making the hard decision to do what is best for the product, rather than doing a hack on program to avoid some push back.

There should be no pushback however, because the fix is simple.

Здравко

@auspugs wrote:
... The main requirement in windows is, that both the hardlink and the folder, is on the same hard drive. ...

Hi @auspugs,

Just one clarification! It's NOT enough "both the hardlink and the folder, is on the same hard drive"! They have to be on the same block unit (in most cases, this mean - same partition). If a hardlink have to be in one partition and target place is in other partition on the same drive, for example, such hardlink is impossible.

auspugs

Learn something new everyday. I do not use hard links much at all. Thank you for the clarifications.

-Rob-

You can just for files by going to "terminal".

then enter on the command line:

ln <existing file> <link to be created>.

This wil create a hard link between the 2 entries.

You can see this by executing:

ls -l <existing file> <link to be created>

You'll see that the number of link (the first number) > 1, and the inode number is the same.

It is in MacOS not possible to create a hard link on directories (as far as I know).

And, how Dropbox handles the hard linked files I don't know. I would expect is doen not recognise the inode number and/or the number of links be the same, so it would create 2 different files, with exactly the same creation/change dates (as these are in the inode admin)