How can I build or skip steps based on the existence of a file or folder?
 

Define a conditional build rule to build if is true (replace FileExists with FolderExists to test for folders). When building the project, if the file/folder exists, the rule will evaluate to -1 (True), and the step will be executed, otherwise it will evaluate to 0 and be skipped. To perform steps in both cases ("if" and "else"), use is false for the else condition (see the Advanced.bld sample for a demonstration).