BASH automate ftp

#! /bin/bash
function fappend \
{
    echo "$2">>$1;
}
 
#credentials
FTPUSER="ftpusername";
FTPPASS="ftppassword";
FTPSITE="ftp.blahblah.com";
 
#file to download
FTPFILE="myfile.zip"
 
FTPTMP="ftp_script.txt";
rm -rf $FTPTMP;
fappend $FTPTMP "open -u $FTPUSER,$FTPPASS $FTPSITE";
fappend $FTPTMP "get $FTPFILE";
fappend $FTPTMP "bye";
lftp -f $FTPTMP;
rm -rf $FTPTMP;