Specify a maven settings.xml file. The specified path can be absolute or relative to the workspace. Shell-like environment variable expansions work in this field, by using the ${VARIABLE} syntax. The file existence is checked on the build agent, if found, that one is used. If not found it will be checked on the master. The settings element in the settings.xml file contains elements used to define values which configure Maven execution in various ways, like the pom.xml, but should not be bundled to any specific project, or distributed to an audience. These include values such as the local repository location, alternate remote repository servers, and authentication information.
There are two locations where a settings.xml file per default may live: The former settings.xml are also called global settings, the latter settings.xml are referred to as user settings. If both files exists, their contents gets merged, with the user-specific settings.xml being dominant.

see also: settings.xml reference