How to loop through each file in FTP directory using a bash script [duplicate]

Possible Duplicate:
How to delete the oldest file over FTP using CURL?

I need to connect to a remote server using a bash script and then delete all files within the directory that are older than 7 days. I'm trying to do this with a for loop within the FTP remote server and I get an error.

#!/bin/sh

HOST='www.ftpserver.com'
USER='username'
PASSWD='password'

ftp -n $HOST <<END_SCRIPT
user ${USER} ${PASSWD}


for i in {ls}
do
 echo "$i"
done

quit
END_SCRIPT
exit 0

The error I get is

We only support non-print format, sorry.
?Invalid command
?Invalid command

Any pointers will help