LFTP

#!/bin/bash
login="USERNAME"
pass="PASSWORD"
host="host.com"
remote_dir='~/location'
local_dir="~/"
base_name="$(basename "$0")"
lock_file="/tmp/$base_name.lock"

trap "rm -f $lock_file" SIGINT SIGTERM
if [ -e "$lock_file" ]
then
    echo "$base_name is running already."
    exit
else
    touch "$lock_file"
    lftp -p 22 -u "$login","$pass" sftp://"$host" << EOF
    set sftp:auto-confirm yes
    set mirror:use-pget-n 5
    mirror -c -P5 --log="/var/log/$base_name.log" "$remote_dir" "$local_dir"
    quit
EOF
    rm -f "$lock_file"
    trap - SIGINT SIGTERM
    exit