Modetc: Move your dotfiles from kernel space

44 points by todsacerdoti 16 hours ago on hackernews | 37 comments

yokoprime | 13 hours ago

I struggle to see a valid usecase for this that isn’t handled by symlinks.

regularfry | 13 hours ago

If I symlink ~/.ssh -> ~/.config/ssh, I still have .ssh in my ~. Whereas if I rewrite it, I don't.

hvenev | 13 hours ago

Will you not have `~/.ssh`? If you have `.ssh .config/ssh` as a rewrite rule, `stat ~/.ssh` will still find it.

txtsd | 13 hours ago

The point is to have a clean home directory.
Abandon hope.

I just treat ~ as a system-owned configuration area, and put my actual files (documents, photos, etc.) in a completely different hierarchy under /.

oftenwrong | 9 hours ago

I have been doing this for decades. My files are in a sub-directory of $HOME. It also makes it very obvious when a piece of software does not treat your $HOME with respect.

SAI_Peregrinus | 5 hours ago

"/home/${USER}" for whatever junk programs are going to stick there, "/home/${USER}/home" for my "real" home directory.

trollbridge | 10 hours ago

You could write a kernel module, then, that just hides certain symlinks from you (which is effectively what this module is).

ComputerGuru | 7 hours ago

On Windows this was always easier because, for some reason, most everyone respected %appdata% compared to XDG_CONFIG_HOME, but also because hidden files wasn’t just a naming convention but an actual separate metadata flag.

Sardtok | 6 hours ago

Always... Except for the decades before this became common. Never a bloated C: root directory. Microsoft even had games store stuff in My Documents\Games at one point. My Documents was a user dir that saw a lot of abuse over the years.

SAI_Peregrinus | 5 hours ago

They still have that, it's just `My Documents\My Games` now. And Visual Studio makes a folder in My Documents for every annual release. And…

Joker_vD | 7 hours ago

That ship has sailed 30 years ago.

user3939382 | 11 hours ago

The use case is that you can actually use your home directory without either (a) hiding files or (b) wading through 40 config files and dirs that XDG ignorant devs put there.

rnhmjoj | 9 hours ago

Hi, author here: whether it's a valid use case depends on your level of OCD, but the difference compared to symlinks or bind mounts is that you will have a clean home: e.g. `ls -la` won't show any "hidden" files.

Also, completely unrelated to my motivation, someone pointed out that modetc could be used to quickly hotfix packages built with Nix. Say that you need to fix a CVE in openssl, normally that would require to rebuild all dependent packages, which takes a long time. Instead with something like modetc you could build just openssl and rewrite /nix/store/<hash>-openssl-3.6.0/ -> /nix/store/<hash>-openssl-3.6.0-hotfix/.

Another application might be replacing some configuration file with placeholders for secrets, with one file with the secrets substituted in, without having to modify it in place, possibly only for a specific UID. This is something you might find useful on NixOS.

tengwar2 | 13 hours ago

One of the annoyances of Linux is working out where configuration information is, following through multiple layers of indirection and files over-riding other files. This looks like adding another layer, another place to look, and if you're reading the man file for a shell (for example) it probably won't even mention that this could invalidate the information contained in that in the man file.

deafpolygon | 12 hours ago

Always check the man pages..

tengwar2 | 6 hours ago

And I said that the man pages would be a part of what you have to examine. 95 pages in the case of bash (that's after running it through troff). man pages were fine when they were three pages long, but their lack of any internal index has become a problem.

Ok, now you might have a dozen files which could contain the information, where the location of each file can be modified by environment variables. It's tolerable if you are working on something you change weekly, but a practical problem if you do it yearly or it's entirely new.

BenjiWiebe | 4 hours ago

'man bash'. Type G. Press PgUp until you see the FILES heading (took one press for my terminal size). There's your list of files. Alternatively, instead of G and PgUp, type /FILES<Enter>.

Of course, this doesn't help at all when software either doesn't have manpages, or doesn't include the list of files in the manpage. Just nitpicking your bash example.

tengwar2 | 3 hours ago

This is HN, not Reddit. You can safely assume that every single person here knows how to use man, particularly if they mention using troff to format it properly. There remains a problem.

skobes | 12 hours ago

Tomorrow: modify man pages from kernel space!

mariusor | 11 hours ago

> working out where configuration information is

Generally, good behaved applications have an entry in their man page that spells out these details for you, so you don't have to work out anything.

user3939382 | 11 hours ago

Unfortunately so many packages these days don’t even have a man page at all let alone one with good config info.

mariusor | 11 hours ago

Well ... hopefully they're open source and all that.

ktm5j | 10 hours ago

You're not wrong. In a worst case scenario I resort to using strace to figure out where a program is reading config from.. from what I understand, if this kernel module is in use then even that approach wouldn't help.

But since the use case is personal dotfiles, I imagine the user isn't going to forget that they set this up.

brianjlogan | 9 hours ago

To be fair the author shows an example of using NixOS. It's absolutely another layer of indirection (probably several) but it does make that usual Linux "fun" less problematic because of its immutable nature and API design.

rnhmjoj | 6 hours ago

> this could invalidate the information contained in that in the man file.

No, it doesn't. The point of modetc is precisely keep both myself and the programs happy: the files are actually stored where I like to keep them, but they can be accessed as if they were stored where the developer intended.

user3939382 | 11 hours ago

I absolutely love this and have wanted to take the time to build this for years precisely because of dotfiles. Thank you!

pimlottc | 10 hours ago

I didn’t understand what this was from the title. Perhaps a better description would be “mod_rewrite for your homedir”

amusingimpala75 | 7 hours ago

From the example:

  # XDG "compliant" programs
  .config/ etc/
  .local/state/ var/lib/
  .cache/ var/cache/
This is the first I’ve heard of using ~/etc instead of ~/.config as $XDG_CONFIG_DIR. Is there any precedent for that?

rnhmjoj | 7 hours ago

Well, it's just the natural extension of the FHS convention to the home directory.

I didn't come up with this idea, though, I think I saw this in a reddit thread and started doing it myself: I like that the directories are visible and follow the usual structure.

godelski | 6 hours ago

Why not push it under a hidden directory? Like ~/.local/etc? If we're reconstructing some of the hierarchy I think it makes sense to group and hide. Isn't the problem that the home folder is getting cluttered?

rnhmjoj | 6 hours ago

Why would I hide them? They're not really special and since I'm organising them with modetc they're not cluttered. For reference, my home looks something like this

    ~
    ├── bin         binaries and scripts
    ├── etc         configuration files
    ├── var
    │   ├── lib     program data
    │   └── cache   program caches
    ├── src         git repositories
    ├── img         pictures
    ├── mail        email in maildir format
    ├── note        text notes, todo
    ├── doc         documents
    └── down        downloads

dividedbyzero | 6 hours ago

But why would I want those directories visible in my home dir?

rustyminnow | 5 hours ago

Why would I want them hidden? I access files in ~/.config almost daily, I think this is a really good idea

simonkagedal | 7 hours ago

The limit of 16 rules is interesting. Where does that come from?

Joker_vD | 7 hours ago

Every time I see yet another dotfile-management solution I just can't help but wonder: maybe it's the dotfiles that are the problem?

ycombinatrix | an hour ago

NixOS solves the same problem without having to mess with the kernel