Where to store application data (non-user specific) on Linux

Question

In my OSGi-based Java app I am developing a bundle to provide the rest of the system with access to the file system. In addition to providing access to the user home directory, I also wish to provide access to a non-user specific area. Exactly what this area will be used for is as yet undetermined, but it will not be for preferences (handled by a different bundle), however it may be used to store data that could change at runtime.

I intend on using the following directories for this purpose:

• Windows Vista & Windows 7: “\ProgramData”.
• Windows XP: “\Documents and Settings\All Users“.
• Mac OS X: “/Library/Application Support”.

Where is a sensible equivalent in Linux and how do I get a handle on it from my Java code?

Answer 1

It depends on what kind of data you're planning on storing. This answer is under the premise that you're storing and modifying data at runtime.

Contrary to what others have suggested, I would recommend against using /usr/share for storage. From the Filesystem Hierarchy Standard:

The /usr/share hierarchy is for all read-only architecture independent data files.

As you're modifying data, this goes against the read-only nature of the /usr subsystem.

A seemingly better place to store your application state data would be /var, or more specifically, /var/lib. This also comes from the Hierarchy Standard. You could create a /var/lib/myapp, or if you're also using things like lock files or logs, you could leverage /var/lock or /var/log.

Have a deeper look at the standard as a whole (linked to above) - you might find a place that fits what you want to do even better.

Like Steve K, I would also recommend using the Preferences API for application preference data.

Answer 2

It depends.

• Global configuration -> /etc/appname

• Read-only, independent of machine architecture -> /usr/share/appname

• Read-only, machine specific -> /usr/lib/appname

• Read-write -> /var/lib/appname

No guarantee for completeness, please check the Filesystem Hierarchy Standard.