12

I've got a source control system at work that I can't modify which scatters a bunch of files in unfortunate places. My IDE expects these folders to be in a single unified location. Normally I'd just symlink everything, but to make things worse, some of the folders must be recursively merged. I have a guarantee that there are no overlapping filenames, but we're talking about thousands of files, more than I'll do by hand.

I've looked into unionfs and aufs, but it's a corporate machine, so no mucking about with the kernel (not to mention the "getting started" docs for these wang chung).

Is there another way to do this?

Jeff Schaller
  • 66,199
  • 35
  • 114
  • 250
Hounshell
  • 303
  • 1
  • 2
  • 7
  • Does your kernel have [fuse](http://fuse.sourceforge.net/) enabled? It is enabled by default under Ubuntu. The point of FUSE is that everything happens in userland, there's no need to muck about with the kernel. Try [unionfs-fuse](http://packages.ubuntu.com/precise/unionfs-fuse) (compile it from source if it isn't included in your release of Ubuntu). – Gilles 'SO- stop being evil' Jun 12 '12 at 22:46

1 Answers1

16

I don't know the tools you are using exactly and how they behave with symbolic links, but you can "copy" whole tree using symlinks (or hard links if you want) automatically using -s option of cp (or -l for hard links).

Let's have a look at below example.

.
├── 1
│   ├── s -> x
│   ├── x
│   ├── y
│   └── z
│       └── 1
└── 2
    ├── a
    │   └── 2
    ├── b
    └── c

If you want co symlink 1/ files to 2/ in current directory, then you can just simply do:

cp -ans "$PWD/1/"* 2/

Now 2/ looks like:

.
...
└── 2
    ├── a
    │   └── 2
    ├── b
    ├── c
    ├── s -> /home/przemoc/links/1/s
    ├── x -> /home/przemoc/links/1/x
    ├── y -> /home/przemoc/links/1/y
    └── z
        └── 1 -> /home/przemoc/links/1/z/1

Explanation of used cp options:

  • -a or --archive
    preserves attributes, links and copies directories recursively (it's in fact alias of -dR --preserve=all)
  • -n or --no-clobber
    prevents overwriting existing files
  • -s or --symbolic-link
    makes symbolic links instead of literal copying

Source file paths have to be absolute in such case (that's why I used $PWD), because cp "can make relative symbolic links only in current directory".

Rui F Ribeiro
  • 55,929
  • 26
  • 146
  • 227
przemoc
  • 436
  • 3
  • 5
  • `cp -s` is new to me, so thank you for that, but this seems to be a one-time operation. I'll need to do this repeatedly, every time I sync with the codebase or add a file. This also doesn't cover cases where the folders need to be merged. For example, if I had ./1/a/3, in my resulting folder I'd want to see ./2/a/[2,3], but I'm pretty sure this copy operation would clobber files. Does that make sense? – Hounshell Jun 12 '12 at 21:58
  • 1
    @Hounshell: You can do it repeatedly, but it won't work with future renames and such, it's simply a copy, only using symlinks. You can possibly go with hard links as long as "unfortunate places" are on the same filesystem. Your description is quite enigmatic, but to preserve some control I would make this unified location consisting only of links (symbolic or hard, whatever suits you better), so it could be easily cleaned and recreated with simple script using `cp -ans` from different places to your one "merged" directory. As for your question of folder merging, it will work fine, don't worry. – przemoc Jun 12 '12 at 22:17