Many applications on Linux systems allow you to alter how they behave at certain
times by altering files containing configuration information. These configuration
files may contain application start-up information, run-time settings and application
shutdown settings. In general, a configuration filename is based on the name
of the application for which it contains settings. Such a naming convention
allows you to more readily determine which configuration file contains settings
for a given application.
It's important to remember that there are two different kinds of configurations
on a Debian system. System-wide configuration affects all users. System-wide
settings are made in the /etc directory, so you generally must be root
in order to change system-wide settings. You might configure the way the system
connects to the Internet, for example, or have web browsers on the system always
start on the company home page. Since you want these settings to apply to all
users, you make the changes in /etc. Sample configuration files in
/etc include /etc/X11/XF86Config, /etc/lynx.cfg,
and /etc/ppp/options. In fact, nearly all the files in /etc
are configuration files.
User configuration affects only a single user. Dotfiles are used for
user configuration. For example, the file ~/.newsrc stores a list
of which USENET (discussion group) articles you have read and which groups you
subscribe to. This allows news readers such as trn or GNUS to display
unread articles in the groups you're interested in. This information will be
different for every user on the system, so each user has his own .newsrc
file in his home directory.