How can I set a global variable that can be accessed from build.gradle and tasks?
To set a global variable
project.ext.set("variableName", value)
To access it from anywhere in the project:
project.variableName
For instance:
project.ext.set("newVersionName", versionString)
and then...
println project.newVersionName
For more information see: http://www.gradle.org/docs/current/dsl/org.gradle.api.plugins.ExtraPropertiesExtension.html
EDIT: As commented by Dmitry, In new versions you can use the following shorthand:
project.ext.variableName = value