Configuration file

A configuration file, a.k.a. config file, is a file that stores data used to configure a software system such as an application, a server or an operating system.

Some applications provide a tool to create, modify, and verify the syntax of their configuration files – sometimes via graphical user interface (GUI). For context, system administrators may be expected to create and modify text config files via a text editor. For server processes and operating-system settings, there is often no standard tool, but operating systems may provide graphical interfaces such as YaST or debconf.

Some computer programs only read their configuration files at startup. Others periodically check the configuration files for changes. Users can instruct some programs to re-read the configuration files and apply the changes to the current process, or indeed to read arbitrary files as a configuration file. There are no definitive standards or strong conventions.