Because `echo test` is not a compound command. Informally, a compound command is a list of commands (`( ... )` or `{ ... }`) or a looping or conditional constr

Because `echo test` is not a compound command. Informally, a compound command is a list of commands (`( ... )` or `{ ... }`) or a looping or conditional construct. See [1] for a precise definition. [1]: https://tiswww.case.edu/php/chet/bash/bashref.html#Compound-Commands https://tiswww.case.edu/php/chet/bash/bashref.html#Compound-...