It is possible to send information (and commands) about the build from the build scripts to TeamCity. This information can be about tests, statistics, build status, and so on.
Tip
More detailed information about build script interaction with TeamCity can be obtained from the documentation located at http://confluence.jetbrains.com/display/TCD8/Build+Script+Interaction+with+TeamCity.
This feature is especially useful when we are using a tool that is not (yet) supported by TeamCity, and hence we do not get the tight integration, such as information regarding the tests being run, and so on.
Such interactions from the build scripts to TeamCity can be done in two ways, which are discussed in the next two sections.