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[4]: what is wrong with FHS?
by Doc Pain on Sun 24th Aug 2008 18:02 UTC in reply to "RE[3]: what is wrong with FHS?"
Doc Pain
Member since:
2006-10-08

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.


That's why they are valid. And you are right, many answers depend on the concepts the person you ask is aware of.

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.


Why? The concent in /usr/local/ is structured exactly the same way the system's directories are structured. So if you know what something is, you can simply conclude where it is.

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


This is correct. While BSD has a strict concept how to define "the OS" and "anything else", other OSes don't. This is due to their nature. If you understood the BSD system, you will know what's "the OS" and what's not.

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.


That's the situation, exactly.

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?


Or /usr/local/var, just as /usr/local/etc. As far as I know, the content of /var is managed through system services (such as the system logger or system database tools), or at least special users and groups have to be created on the system to put things in /var (for example "CUPS Owner" or "MySQL Deamon").

For that matter, why isn't base stuff under /base/ and local stuff under /local/? That would really make it all clearly different.


Yes, if you could exactly differ between both.


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) [...]


There are the basic system games, but most people won't call them games. The programs bcd, factor, grdc, number, ppt, random, strfile, caesar, fortune, morse, pom, primes, rot13 and unstr are... toys?

why are games in /usr/local/games and not /usr/local/bin?


I've never heared of /usr/local/games. Installed games go to /usr/local/bin (and their components to lib, share respectively).

/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.


Thanks for giving the layout of /opt, I haven't seen /opt for years, I still do remember something like /opt/kde/share...

So /opt does seem to contain structures like those created by the PC-BSD's PBI system: one entry per program name, bin and libs beneath; for compatibility, symlinks from /usr/local subtrees.

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


In Linux, yes. In BSD, no. See "man hier", everything is explained. Of course, the question "Why?" remains.

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/?


You're completely right: The definition of "temporary" depends a lot on how you use a media. Plug in, plug out, use today, not tomorrow, well, that would be temporary. An external USB disk that is mounted all the time, okay, not temporary.

But *shouldn't* there be a structure [in /tmp]? 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".


That would be helpful if your system would not clean /tmp automatically. You would have a better idea, for example, who (which program) placed files there, you you could see from their name if it's okay to remove them.

Anyway, at system shutdown, /tmp usually disappears.

Do lock files go in /tmp? Lock files tend to matter, yet I see e.g. /tmp/.X0-lock.


I've seen lock files for programs inside "dot dirs" inside the user's home directory, ~/.netscape/lock for example. And there's /var/spool/lock, too.

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?


That would be a matter of the maintainers of this particular software. As far as I remember, KDE creates own subtrees in /tmp, but for documentation... it's not that you can "man kdehier"... :-)

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


Not blame those who do ignore it? If I don't obey the traffic rules, it it the rules' fault?

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


I think this is Linux-specific again.

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.


At least in BSD, theres some kind of standardization (see section "var" in "man hier": "multi-purpose log, temporary, transient, and spool file". And sadly, I don't have a more precise answer because often, applications do things on their own.

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.


Yes, I intended it to be understood this way. :-) The content of /var should be present without any disappearings while the system is running. Anything else would be a catastrophe.

"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. [/q]

A common way is to use the home directory of the user to which's name the HTML content is registrated. But this doesn't have to be, for example, if an automated system is running that's not registrated to any user on the system. Another concept is to symlink files from a user's home directory into a directory belonging to the HTTP server application, so you could place "un-registrated" content there directly.

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.


As you introduced, the knowlegde of existing standards and concepts, their interpretation and their de-facto use are very individual. Just imagine what happens when people start questioning and interpreting the traffic rules. Just a general consensus helps he

Reply Parent Score: 3

sorpigal Member since:
2005-11-02

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


This is correct. While BSD has a strict concept how to define "the OS" and "anything else", other OSes don't. This is due to their nature. If you understood the BSD system, you will know what's "the OS" and what's not.
"

I meant to say that *even in BSD* it's hard to be sure, as a user, whether something came with the base or was part of an add-on. "User" here is both system admins and regular users.

As far as I know, the content of /var is managed through system services (such as the system logger or system database tools), or at least special users and groups have to be created on the system to put things in /var (for example "CUPS Owner" or "MySQL Deamon").

An interesting definition. OK, so how does the author of a system service know how to answer the questions about what structure /var/ has?

"why are games in /usr/local/games and not /usr/local/bin?


I've never heared of /usr/local/games. Installed games go to /usr/local/bin (and their components to lib, share respectively).
"

Perhaps in BSD this might be true, but on my system there's /usr/games and /usr/local/games. Some games don't put their binaries there, most do. This is part of the FHS, see here: http://www.pathname.com/fhs/pub/fhs-2.3.html

So /opt does seem to contain structures like those created by the PC-BSD's PBI system: one entry per program name, bin and libs beneath; for compatibility, symlinks from /usr/local subtrees.


/opt only *sometimes* contains this structure. Each program has a subdirectory, after that it's up to the whim of the author.

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


In Linux, yes. In BSD, no. See "man hier", everything is explained. Of course, the question "Why?" remains.
"

I'd like to believe that no violations exist, but I just don't. Nobody is that perfect.

"But *shouldn't* there be a structure [in /tmp]? Some kind of convention for temporary files that an application 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".


That would be helpful if your system would not clean /tmp automatically. You would have a better idea, for example, who (which program) placed files there, you you could see from their name if it's okay to remove them.

Anyway, at system shutdown, /tmp usually disappears.
"

All *nix systems clean /tmp on start. This is not a workaround for a broken system that doesn't clean /tmp. Systems rarely clean /tmp while the system is up. I don't know about you but I very rarely reboot my computers, except to patch the kernel and upgrade hardware. Can we really rely on boot-time cleaning?

Secondly, even if we're not worried about crufty junk accumulating it seems to me that it would be useful to provide more clarity. Don't tell me "just don't ever look in /tmp" because sometimes you have to... and sometimes you're writing a program that has to work with temporary files. Isn't it better to have a clear place to put things?

I've seen lock files for programs inside "dot dirs" inside the user's home directory, ~/.netscape/lock for example. And there's /var/spool/lock, too.


This is a perfect example of the problem: The correct behavior is not known so a developer makes something up. I'd like to avoid this kind of thing,

"I tend to blame the standard when it gets ignored.


Not blame those who do ignore it? If I don't obey the traffic rules, it it the rules' fault?
"
There are two problems with that analogy: (1) Laws are enforced, standards aren't. (2) When you have a rule no one obeys you have a bad rule, not bad people.

(concerning /var structure)
At least in BSD, theres some kind of standardization (see section "var" in "man hier": "multi-purpose log, temporary, transient, and spool file". And sadly, I don't have a more precise answer because often, applications do things on their own.

And each application doing its own thing is a problem because then there's no consistency. This is why I say the FHS has problems.

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


In ~/public_html? :-)
"

In whose home directory? ... [/q]

A common way is to use the home directory of the user to which's name the HTML content is registrated. But this doesn't have to be, for example, if an automated system is running that's not registrated to any user on the system. Another concept is to symlink files from a user's home directory into a directory belonging to the HTTP server application, so you could place "un-registrated" content there directly. [/q]

But in the FHS there is no place for a directory belonging to the HTTP server except for /usr/lib/httpd (or under local as you choose) and somewhere in /var. Yet a web sites files are not exactly run-time modified and clearly should be under /home, but no user in /home owns them, so...

The best answer I have apart from /var is /home/www on a system where a user named www executes the httpd.

This once again goes back to my point: The FHS has problems, mostly that it doesn't answer questions it should and partly that it's terribly, arbitrarily inconsistent. People who want to radically overhaul it are usually misguided, but they frustration springs from very real issues.

BTW, your reply looks truncated. Was it?

Reply Parent Score: 2

Doc Pain Member since:
2006-10-08

I meant to say that *even in BSD* it's hard to be sure, as a user, whether something came with the base or was part of an add-on. "User" here is both system admins and regular users.


A means to determine it is by looking at the path of an installed program:

% which lpq
/usr/bin/lpq

Ah, this one belongs to the OS.

% which lpstat
/usr/local/bin/lpstat

This has been installed afterwards. (Now it's possible to use the tools provided by the package management system to find out which application had installed it.)

Furthermore, you can read from the creators of the BSD which things they provide (with their OS) and which they don't. For example, the default installation of FreeBSD and OpenBSD differ in regards of what does belong to the base system.

Other questions coming into mind could be: Why is a name server part of the base system? Why is a DHCP server not part of the base system? I'm sure you can imagine similar considerations.

OK, so how does the author of a system service know how to answer the questions about what structure /var/ has?


Usually from "man hier" or the respective description - if one is available. If not, well, I think the author starts guessing and finally implements something on his own.

I'd like to believe that no violations exist [in BSD], but I just don't. Nobody is that perfect.


I won't claim there is no exception. Often, I find applications using share/ and lib/ directories in a similar way (e. g. to put icons there). There are recommendations, but not everyone uses them. So it's completely possible in the BSDs, as it is in Linux.


All *nix systems clean /tmp on start.


No. For example, if you set clear_tmp_enable="NO" in /etc/rc.conf in FreeBSD, the content of /tmp will be kept between reboots.

I don't know about you but I very rarely reboot my computers, except to patch the kernel and upgrade hardware.


At home, my computers run just as long as I use them or as long as they've got something to do. At work... well, who reboots servers? :-)

Can we really rely on boot-time cleaning?


It's a system setting, the maintainer of the system should know. And it's the standard behaviour to start with an empty /tmp, as far as I know.

Secondly, even if we're not worried about crufty junk accumulating it seems to me that it would be useful to provide more clarity. Don't tell me "just don't ever look in /tmp" because sometimes you have to... and sometimes you're writing a program that has to work with temporary files. Isn't it better to have a clear place to put things?


Definitely. Maybe you know the term "file disposition" from IBM mainframe OS architectures / JCL. You can define how a file will be handled during a job, e. g. it's deleted after the job has finished (often welcome solution), or it should be kept for further use (sometimes useful, mostly for diagnostics).

But I still think the term "temporary" indicates that something is not very useful to the user, but maybe to other programs.

This is a perfect example of the problem: The correct behavior is not known so a developer makes something up. I'd like to avoid this kind of thing,


Exactly. But when we suggest a "correct behaviour", it should be documented in an understandable way. I'm not sure who would be responsible for this, maybe the creators or maintainers of an OS? But then, what about cross-platform applications? And when we're talking about Linux, who should develop a common standard there? And would the different distributors follow it?

There are two problems with that analogy: (1) Laws are enforced, standards aren't. (2) When you have a rule no one obeys you have a bad rule, not bad people.


Interesting look at the nature of rules, but understandable.

And each application doing its own thing is a problem because then there's no consistency. This is why I say the FHS has problems.
[...]
This once again goes back to my point: The FHS has problems, mostly that it doesn't answer questions it should and partly that it's terribly, arbitrarily inconsistent. People who want to radically overhaul it are usually misguided, but they frustration springs from very real issues.


Other arguments could be "never touch a running system" or "don't ask why it works, it just works". Sooner or later, this can lead into real problems. I see the problems simply by following your questions: Many of them cannot be answered completely, and answers sometimes lead to the inconsistencies you mentioned. Concepts leading to such answers are far away from a mandatory standard.

BTW, your reply looks truncated. Was it?


Maybe I exceeded the char[8000] limit, but the preview was complete. "Just a general consensus helps here." should be the last line, it's possible that I didn't press the keys strong enough. :-)

Reply Parent Score: 2