Pour créer le répertoire toto avec tous les répertoires parents :

mkdir -p /home/repertoire/toto

Pour créer une arborescence :

mkdir -pv dir{1,2,3}/subdir{1,2,3}

mkdir: created directory `dir1/subdir1'
mkdir: created directory `dir1/subdir2'
mkdir: created directory `dir1/subdir3'
mkdir: created directory `dir2/subdir1'
mkdir: created directory `dir2/subdir2'
mkdir: created directory `dir2/subdir3'
mkdir: created directory `dir3/subdir1'
mkdir: created directory `dir3/subdir2'
mkdir: created directory `dir3/subdir3'