14

Possible Duplicate:
Meaning of directories on Unix and Unix like systems

I'm confused about the different uses for 3 of the standard "root-level" folders: /var /etc /usr

What are the different use cases for these directories?

Community
  • 1
Robert Ross
  • 461
  • 3
  • 6
  • 10

2 Answers2

17

"/etc" is used for configurations (.conf files etc). here you find all the configs and settings for your system.

"/usr" is used for "user programs". Usually your package manager installs all the binaries, shared files etc. from all programs here (except config files, which go to /etc). You can check /usr/bin for binaries, /usr/share for shared files (media, etc), /usr/share/doc for documentation,...

There is also an "/opt" folder, where there are "other" programs usually put (mostly binary programs, or programs installed from other sources (not the default package manager). Some programs like that (usually compiled) also go to "/usr/local"

"/var" is usually used for log files, 'temporary' files (like mail spool, printer spool, etc), databases, and all other data not tied to a specific user. Logs are usually in "/var/log", databases in "/var/lib" (mysql - "/var/lib/mysql"), etc.

mulaz
  • 10,682
  • 1
  • 31
  • 37
  • 1
    What does lib in varlib mean? Why lib? – Pacerier Aug 22 '17 at 05:00
  • @Pacerier lib is short for library/libraries. – devios1 Aug 22 '17 at 17:10
  • @devios1 still doesn't really explain why that folder is so called. mysql is not a library. – samlaf Feb 05 '23 at 06:17
  • @samlaf: `/var`, as the name implies, is for _variable_ (read/write) data that's _persistent_ across reboots (unlike temporary data in `/tmp`), in contrast with the (mostly) read-only `/usr`. As for `/var/lib`, in this particular case the `lib` subdir means "library" only in a very broad sense, as it actually stands for any specific software or package, as opposed to more general, system-wide subdirs like `/var/log` which don't belong to any particular package. MySQL example, its read-only files go to `/usr/*/mysql`, settings at `/etc/mysql`, and read/write databases at `/var/lib/mysql` – MestreLion Jun 11 '23 at 10:26
3

The /etc/ directory is a common location to put configuration files. (But not the ONLY one by any means.)

The /var directory is the location for "variable" things like logs, running process ID pointer files, spool directories, and other things important for running services.

The /usr/ directory is where user-accessible applications are generally located. Also a case of "by no means all".

Magellan
  • 4,451
  • 3
  • 30
  • 53
  • So what would the definition of /usr/etc be? – Robert Ross Apr 29 '12 at 23:21
  • config files for user-supplied application, probably. Personally, I prefer to keep THOSE things over in /opt if they're not part of a package provided with the OS or Distribution. – Magellan Apr 29 '12 at 23:27
  • Mind you, none of this is a "rule". It's more tradition and convention and it's transgressed often enough in practice, but is generally-considered a good idea to follow. – Magellan Apr 29 '12 at 23:27
  • Right, that's more what I'm aiming towards is best practices. Perhaps a title change? – Robert Ross Apr 29 '12 at 23:36