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The practical (Unix) problems with .cache and its friends

Zopieux

What an objectively terrible, counter-productive take on what is an otherwise simple and solved problem.

Use an appropriately named folder (hi Nvidia, I hate your ".nv") in XDG_CACHE_HOME like every well behaved program in the past decade and let the disk space utilities solve the visibility issue.

quotemstr

It's because of articles like this that computing is an inconsistent mess. When you make a technical proposal in public like this, it's your responsibility to ask yourself "What would it look like if everyone did this?". If the answer is "a personal kind of hell", don't make the proposal.

walth

Also pretty easy to implement disk quotas on a modern system.

Heck, you could even display a warning or the top directories consuming space upon login.

Not a great take - this is a operations problem, not a design problem.

Varriount

What software should be doing is using XDG_CACHE_HOME, if it is set (along with the other XDG environment variables). That way cache directories will be where the user expects.

quotemstr

The XDG specification (https://specifications.freedesktop.org/basedir-spec/latest/) is

  1. short and easy to read,

  2. good for users, and

  3. can be implemented in five minutes.
If we can't have programs follow this simple decades-old convention, we have no hope whatsoever of voluntary consistency in our computing world. It's literally because of the mentality espoused in this article that we can't have nice things.

Unfortunately, we have nothing but social pressure and incensed HN comments to get developers to follow it. That's why the mobile world adopted a "you shall" model: a developer won't spent five minutes to save a million years of user time unless there's some social or technical guardrail forcing his hand.

WhyNotHugo

Agreed. What op wants in this case, is for XDG_CACHE_HOME to default to ~/cache when unset.

The idea is quite reasonable: suddenly all tools that show disk usage will show this directory clearly and you can easily find what’s eating up you space with the same usual tools as always.

Macha

I think they'll find they're in the minority on that opinion, so they should just set XDG_CACHE_HOME, and maybe symlink ~/.cache to ~/cache for those programs that have just hardcoded ~/.cache

mystified5016

Are dot folders actually a problem? I have show hidden files turned on globally everywhere always. I don't really understand how people operate otherwise.

WhyNotHugo

So it sounds like having them hidden is a problem for you, given that you've disabled this behaviour globally.

Some folk just don't want to configure every single application to unhide them (or have no idea that they exist in the first place).

hiccuphippo

> Dear everyone writing Unix programs that cache things in dot-directories (.cache, .local, etc): please don't. Create a non-dot directory for it.

If it doesn't live inside ~/.cache or ~/.program/cache then I won't know if I can delete it or not.

If you are not putting your cache in one of those folders, I'd expect the application itself to have a clear-cache option or for it to do it automatically from time to time.

jmclnx

To me, on OpenBSD that kind of breaks the purpose of unveil.

Firefox and chrome on OpenBSD is patched to use pledge and unveil. That restricts where these programs can read/write data. I would not want a program to have access to all cache data for every program.

To me, if you see dir cache, you can clear it. In fact, I have a cron job to clear cache data older than a week for Firefox. No issues doing this for many years.

lloeki

> I would not want a program to have access to all cache data for every program.

Then XDG_CACHE_DIR doesn't change anything?

The path is going to be $XDG_CACHE_DIR/$PROGRAM which is what would get allowed (and neighbour subdirs disallowed); no program would get to see the others' cache.

I just checked and I have a ~/.cache/firefox right there.

Having it at a single root point means it's trivial to make all cache ephemeral in any way one chooses.

jmclnx

I am not sure if XDG_CACHE_DIR is set or not. But for some reason I think it is unveiled in the firefox config file in /etc. My OpenBSD system is powered down right now so I cannot check.

rererereferred

How do you know it's a cache dir and not configuration or something else? I don't say programs should have access to the cache directories of other programs just to their own inside ~/.cache.

jmclnx

If I see the name cache I hope it is cache :)

So far that has not failed me yet, maybe some day I will get burned.

yjftsjthsd-h

Can ex. Firefox not unveil($HOME/.cache/firefox) ? Or actually I'd prefer unveil($HOME/.cache/firefox/$PROFILE)

jmclnx

Not sure what is being asked.

But there is a config file in /etc on OpenBSD that is used to determine what directories are unveiled. I do not remember the name.

So you can customize that as you see fit, veiling or unveiling items.

ignoramous

> I'd expect the application itself to have a clear-cache option or for it to do it automatically from time to time.

Android has this. Though, the reason they included a "cache partition" back in the day was to make sure there was always enough space to download flash system.img over-the-air (as wiping clean the cache partition would provide enough room).

bityard

I usually agree with the things that Chris writes but this isn't one of them.

For starters, ~/.cache was invented because everyone was doing their own thing and the previous situation was FAR worse.

I don't agree with eliminating the concept of dot directories in unix just because some people haven't learned about them yet.

And of course he acknowledges that their environment is unique.

What I would do: run a script to symlink '.cache' to 'cache' in entry users home dir. Then it's not hidden anymore.

yonatan8070

I don't think that putting cache in .cache is bad, as long as everyone does it. But some programs (like VS Code and Chromium) decided that .config is a good place for their cache and local files, which I think is a bigger problem.

c0l0

XDG_CACHE_HOME, as mentioned by numerous other posters, is a good remedy to deal with this kind of cached-artifacts-sprawl - but it does need a will to cooperate and care from the original software developer in the first place, which ain't a given.

So does another standard that I've come to appreciate in all software that supports it: CACHEDIR.TAG (https://github.com/LineageOS/charter/blob/main/device-suppor...) - I'm just here to spread the word! ;)

c0l0

Dammit, my clipboard manager messed up the link I was about to post, and now it's too late to edit :/

For posterity: https://bford.info/cachedir/ is what I was meant to link to above. Sorry for the inconvenience.

codetrotter

I went on GitHub to see if anyone was using this cachedir tag signature. Found many results so that’s cool :)

But ironically, if I’m reading correctly the command line ncurses based disk usage tool ncdu seems like it will intentionally ignore any directory that has this cachedir tag.

https://github.com/rofl0r/ncdu/blob/a216bc2d35b6edf4dadf5535...

https://github.com/rofl0r/ncdu/blob/a216bc2d35b6edf4dadf5535...

Which is the very sort of thing the original post was complaining about that happens with invisible .cache directories too :^)

klodolph

I get kinda pissed at any program that creates a visible directory.

hooli_gan

Also dot files and directories in my home. Why do programs decide to treat my home like a junkyard?

NewJazz

At one point I markedy home directory as read only. Subdirs were read-write.

The number of programs that would silently or cryptically fail was too much. Had to cave in and allow them free reign.

nimih

If your users are not fluent enough in Linux/Unix tools and conventions to be able to figure out how large a single standardized dotfile in their home directory is, I really don’t think the problem is “application developers are following a well-known standard.”

rollcat

"Dot" files are a terrible idea to begin with.

It began as a dirty hack in "ls", in order to skip displaying "." and "..", it looked only at the first character of a file name. Exact string comparison is costly, and early UNIX could not afford that price.

Then people noticed that other ".whatevers" will also be "hidden", unless "-a" is specified.

Then it snowballed into hell.

Both Plan 9 and OS X tried to fix it, with "~/lib" and "~/Library" respectively, but especially as the latter was and is a certified UNIX, there's no avoiding a hundred random dot files and directories. I try to delete stuff I know I won't need again but...

    $ uname
    Darwin
    $ ls -a | grep '^\.' | wc -l
      61
Twenty of those were important enough for me to put them in version control, the rest is random crap. Even Hammerspoon, a *native* Mac app that hooks itself deeply into the OS APIs, uses its own dot directory.

Advice for all programs: follow the XDG spec[1]. Advice for OS vendors: default them to something more reasonable; ~/Library sounds appealing since we already use ~/Desktop, ~/Downloads, and so on.

[1]: https://specifications.freedesktop.org/basedir-spec/latest/

pasc1878

Hidden files with . are just not a good design.

the `du -s *` really shows that.

I wish they showed by default and you added a term to hide them.

Apple does not help here as they used to use ~/Library/Caches for all but now with sandboxes each Container has its own Cache and the sirectory they are in sometimes has a random name not simply the app name.

dlachausse

Fun fact, hidden dot files were not designed, but were the result of an early UNIX bug that users and developers came to depend on…

http://xahlee.info/UnixResource_dir/writ/unix_origin_of_dot_...

zahlman

> As noted by Haelwenn /элвэн/, a plain 'du' will find such dotfiles. The problem is that plain 'du' is more or less useless for most people; to really take advantage of it, you have to know the right trick (not just the -h argument but feeding it to sort to find things). How I think most people use 'du' to find space hogs is they start in their home directory with 'du -s ' (or maybe 'du -hs ') and then they look at whatever big things show up. This will completely miss things in dot-directories in normal usage.

I don't understand. `du` indeed finds the dotfiles (and dot-folders); and if their contents are large, then they'll be noticed by someone who "looks at whatever big things show up". It's not at all clear to me why I'd be using a combination like `du -s *`.

Besides, there are more ways to hide the data from yourself (e.g. symlinking your desktop from somewhere else).

That said, I have found `ncdu` invaluable for navigating through the results, swapping between different views etc.

> And on Linux desktops, I believe that common GUI file browsers will omit dot-directories by default and may not even have a particularly accessible option to change that (this is certainly the behavior of Cinnamon's 'Files' application and I can't imagine that GNOME is different, considering their attitude).

"Cinnamon's 'Files' application" is Nemo, wherein you can right-click on any window and check the "show hidden files" option in the context menu (admittedly a strange placement, since it's a global setting).

atq2119

I'd like to second the recommendation of ncdu.

If anything can be taken home from this article, it's that perhaps desktop environments need to do a better job helping users to understand disk utilisation.

The article's own recommendation would just make things worse. Application authors should stick to XDG standard directories.