셀스크립트 에러

안녕하세요

책에서 대소문자 셀스크립트 에서 에러가 발생하였습니다

[root@root kk]# ls -al
total 36
drwxr-xr-x  2 root root 4096 Jun 23 10:59 .
drwxr-xr-x  3 root root 4096 Jun 23 10:55 ..
-rw-r--r--  1 root root    0 Jun 23 10:46 AAA
-rw-r--r--  1 root root    0 Jun 23 10:46 CCC
-rw-r--r--  1 root root    0 Jun 23 10:46 WEB
-rwxrwxrwx  1 root root  104 Jun 23 10:59 kk.sh

[root@root kk]# cat kk.sh
#!/bin/bash
for i in ls [A-Z]*
do
newfilename='echo $i | tr "[A-Z]" "[a-z]"'
mv -i $i $newfilename
done

[root@root kk]# ./kk.sh
mv: when moving multiple files, last argument must be a directory
Try `mv --help' for more information.
mv: when moving multiple files, last argument must be a directory
Try `mv --help' for more information.
mv: when moving multiple files, last argument must be a directory
Try `mv --help' for more information.
mv: when moving multiple files, last argument must be a directory
Try `mv --help' for more information.
[root@root kk]#
위와 같은 에러가 발생하네여.

원인을 못찾겠습니다