All QNX BSPs ship with a buildfile, which is a type of control file that gives instructions to the mkifs command-line utility to generate an OS image. The buildfile specifies the particular startup program, environment variables, drivers, etc. to use for creating the image. The boot script portion of a buildfile contains the sequence of commands that the Process Manager executes when your completed image starts up on the target.
The QNX System Builder perspective provides a convenient graphical alternative to the text-based buildfile method. While it hides most of the gruesome details from you, the QNX System Builder perspective also lets you see and work with things such as boot scripts.
The QNX System Builder perspective stores the boot script for your project in a .bsh file. If you double-click a .bsh file in the System Builder Projects view, you'll see its contents in the editor.