Originally we had the Bourne shell ( sh ), which later originated the Bourne Again shell ( bash ) , Z Shell ( zsh ) and others. Some commands are specific to the shell being used. In the diagram below we make shell specific commands explicit.

	classDef shell stroke-width:2px,stroke:yellow;
	class sh shell
	class bash shell
	class zsh shell
	class fish shell
	sh --> bash
	sh --> zsh

	sh --> su
	sh --> cat
	sh --> touch
	bash --> source