#!/bin/bash
# see here: https://stackoverflow.com/a/32235669

#get username and password
USER=username                   #Your username
PASS=password                   #Your password
HOST="myftpserver.com"          #Keep just the address
LCD="~/Desktop/localfolder"     #Your local directory
RCD="/users/user"               #FTP server directory

lftp -f "
open $HOST
user $USER $PASS
lcd $LCD
mirror --continue --reverse --delete --verbose $LCD $RCD
bye
"