Linked by Thom Holwerda on Sat 23rd Aug 2008 15:37 UTC
Editorial Earlier this week, we ran a story on GoboLinux, and the distribution's effort to replace the Filesystem Hierarchy Standard with a more pleasant, human-readable, and logical design. A lot of people liked the idea of modernising/replacing the FHS, but just as many people were against doing so. Valid arguments were presented both ways, but in this article, I would like to focus on a common sentiment that came forward in that discussion: normal users shouldn't see the FHS, and advanced users are smart enough to figure out how the FHS works.
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RE[3]: what is wrong with FHS?
by sorpigal on Sun 24th Aug 2008 11:48 UTC in reply to "RE[2]: what is wrong with FHS?"
sorpigal
Member since:
2005-11-02

You're bringing up valid questions.

These are not questions; they're rhetorical or, rather, they're designed to make you think of the answers and wonder whether they are truly correct. I already know the answers to them, as far as I'm concerned, it's just that the answers vary depending on who you ask.

This is really something (along with the lib/ problem) that I find a bit strange in Linux. In BSD, there's a differnce between "the OS" and "installed packages", while Linux does not have this kind of separation. BSD puts system's stuff in /etc/, and local (not to the system belonging) parts in the respective /usr/local/etc/ directories. You can conclude the nature of a file from its name and it place within the file hierarchy.

I knew some BSD user would mention this. I hate that in BSD some configuration goes under /usr/local/--this makes no sense! Why isn't it under /etc/local/? That would be much better.

And no, you can't always be sure (as a layman) whether something is part of the "base OS" or not.

In general, additional software should go into /usr/local/ where the basic subtrees of the system (etc/, lib/, include/, bin/, share/) are replicated with the respective purpose.
But as I mentioned before, it's hard to say which things do not belong to the system because Linux distributions do not differ between OS and installed packages; in fact, the "OS part" is a set of packages chosen by the creator of the distribution. Rule: Everythin within /usr/local/ is extra stuff, everything outside is the system (mountpoints and home directories not mentioned here).

Defining "additional" is hard. For the BSD guys it's ports, fine. For Linux distributions it's either things not managed by the package manager or things not packaged by the distribution vendor, or it's a mess. Usually it's a mess even if one of the other rules was supposed to apply. If you make a strict distinction between local and base, why is there no /var/local? /etc/local? For that matter, why isn't base stuff under /base/ and local stuff under /local/? That would really make it all clearly different.

Games should obey this rule.

But why are games a special class of binary? Why do I have /usr/games/? Supposing on BSD there are no base-system games (I really don't know) why are games in /usr/local/games and not /usr/local/bin? On Linux some games are in games, some are in bin. Some game-related binaries (like wesnothd) are in games when they're not really games at all. If games are a special class of binary, why not development-related binaries like gcc or bison? Why not make database utilities special too?

And /opt/... I think it has initially been intended as a directory that contains extra stuff that does not obay the subtree rule, i. e. no etc/, lib/ or bin/ separation, instead a name of the application with its own subtree.


/opt typically has this structure:
/opt/appname/etc/
/opt/appname/bin/
/opt/appname/lib/
/opt/appname/share/
Unless it has some other structure or none at all.
But even if you were right, why should there be any exception to the rules officially allowed? I despise "standards" that say "You must do it this way to conform, unless you don't feel like it in which case we'll say you conform anyway." So useless.

/mnt is intended as a temporary mount point for the system administrator (according to man hier).

/media is intended for (usually auto)mounted media, it contains a subtree for the devices (e. g. /media/cdrom, /media/dvd, /media/stick) or mountpoints are created from a label provided by the media itself or by the class of the drive (man geom).

Allthough the access to /floppy and /cdrom is much easier than their successors within /media (due to less typing), these mountpoints may already be deprecated.


You say this and the standard says this, but do the users know this? Do distributions obey? I see frequent violations.

What's more, defining "temporary" is hard. Is a flash drive temporary? I certainly think so: It is not part of the system and it may come and go. But you just placed stick/ under /media/, which makes sense in a lot of ways, too. I would have defined dvd and cdrom drives as temporary, had you asked me. What about an external USB cdrom drive? Why should it be in /media/?

"Is there any structure to /tmp?


No, because programs or users that use /tmp should keep an eye on the stuff they do on their own. This is because /tmp may disappear at system shutdown, or, may be empty after system startup, for example when /tmp leads to a RAM disk or some system setting clears /tmp at startup. It's the system's waste dump. :-)
"

It's easy to say no, because that's what always has been. But *shouldn't* there be a structure? Some kind of convention for temporary files that an application t relies on during run vs. ones it just throws out and does not care if it sees again. Maybe distinguish tmp files created by "the OS" and "the user's applications". Do lock files go in /tmp? Lock files tend to matter, yet I see e.g. /tmp/.X0-lock. Many applications now create a subdirectory in /tmp to hold their files. Is there any documentation on when this should be done or how to name the directories?

If e.g. lock files are violations, why is it so common? I tend to blame the standard when it gets ignored.

"What's the difference between /usr/doc and /usr/share/doc?


Only the last one should exist, an assumption from priority and precedence considerations.
"

This is your opinion. I agree, but since I see /usr/doc/ frequently it appears we are in a minority.

"What directories can I expect to find in /var?


Usually databases and logs that are created and managed by programs, not by the user.
"

Forgive me if I desire a more precise answer. Does each app make its own subdirectory in /var/? In /var/lib/? Or do you first make a subdirectory for purpose, then for app, like /var/run/appname/ or /var/lock/appname/? I see all of these things being done without agreement, rhyme or reason.

Is there any restriction on creating more directories directly in /var/? Or, if you believe each app should make its own anyway, what is the naming convention and are there any restrictions on creating diretcortories not obeying that convention?

If it's okay to lose it - /tmp. If it should be kept - /var.


Correction: If it's okay to lose it between reboots /tmp, otherwise /var. Some things in /tmp are *not* good to lose while an app is executing.

"If I have a web site where should the files for it be stored?


In ~/public_html? :-)
"

In whose home directory? I'm not trying to be difficult, it's not as if I can't answer these questions, it's just that nobody agrees on the answers. You can always give one, and I can always give one, but that doesn't make it correct and it doesn't make it likely that someone else will think the same thing and do it the same way.

"If you think you know the answers to some of these questions I have a surprise for you: *every unix does some of them differently and even distributions of Linux can't all agree*.


You see this from my explainations, and some reasons why it is so. Alltough much of the stuff is well intended, there are inconvenient uses of the existing structures, maybe due to sloppyness, or due to general problems of interpretation. There are many differences between the many Linux distributions and among the UNIXes, too.
" [/q]

I know why these things are the way they are, I know most of why they got that way and I know most of the differences that will be found. Your explanations are just that: yours. If there were right answers that everyone agreed on and conventions that most people followed correctly then there would be no problem.

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