Initially conceived as a simply testing and validation tool for developers only, the UEFI shell has grown to widespread adoption in the industry. Once it was realized that the shell was becoming such a popular and useful tool, the effort was made to organize and direct future developments. Due to the disparate nature of the environments the UEFI shell found uses in, supporting one single technology was inadvisable. This article explores the evolution of the UEFI shell from an in-house development tool, through its formal conception and specification.