The BASH ‘brace expansion‘ feature can be used to create whole directory trees using a single command.
$ mkdir -p root/{1/{1.1,1.2,1.3},2,3/{3.1,3.2/{3.2.1,3.2.2}}} $ tree . `-- root |-- 1 | |-- 1.1 | |-- 1.2 | `-- 1.3 |-- 2 `-- 3 |-- 3.1 `-- 3.2 |-- 3.2.1 `-- 3.2.2