It's simply a block, and fish specifies blocks with "begin" and "end". begin; cat file_1; cat file_2 | grep something; end | sort (note that this is disti

It's simply a block, and fish specifies blocks with "begin" and "end". begin; cat file_1; cat file_2 | grep something; end | sort (note that this is distinct from a "subshell", which has a separate environment and typically is more confusing than helpful. In this particular case it doesn't matter)