O comando é mv foldername newfoldername
Exemplo ( mv
/tmp/huy
a /tmp/huyN
):
cd /tmp
/tmp$ mkdir huy
/tmp$ touch huy/testfile
/tmp$ mv huy huyN
/tmp$ ll huyN/
total 24
drwxrwxr-x 2 user user 4096 Feb 21 09:48 ./
drwxrwxrwt 36 root root 20480 Feb 21 09:48 ../
-rw-rw-r-- 1 user user 0 Feb 21 09:48 testfile
/tmp$
Mais informações: man mv