Shareable/Unshareable, Static/Variable Data

Data on a UNIX system can be classified according to the following criteria: shareable data can be common to several computers in a network, while unshareable cannot. Static data must not be modified in normal use, while variable data can. As we explore the tree structure, we will classify the different directories into each of these categories.

Note that these classifications are only a recommendation. It is not mandatory to follow them, but adopting these guidelines will greatly help you manage your system. Also, keep in mind that the static/variable distinction only applies to general system usage, not its configuration. If you install a program, you will obviously have to modify “normally” static directories, i.e.: /usr.