script to backup file to dropbox

backup.sh

!/usr/bin/bash
DROPBOX_KEY='XXXXXX'
FILENAME=XXXXXX
cd XXXXXX
tar czf $FILENAME XXXXXX > /dev/null
/usr/bin/python - <<END
import dropbox
from dropbox.files import WriteMode
from os.path import getsize, basename
dbx = dropbox.Dropbox('$DROPBOX_KEY')
CHUNK_SIZE = 20 * 1024 * 1024
f = open('$FILENAME', 'rb')
file_size = getsize('$FILENAME')
result = dbx.files_upload_session_start(f.read(CHUNK_SIZE))
cursor = dropbox.files.UploadSessionCursor(session_id=result.session_id, offset=f.tell())
dbx_path = '/backup/' + basename('$FILENAME')
commit = dropbox.files.CommitInfo(path=dbx_path, mode=WriteMode.overwrite)
while f.tell() <= file_size:
    if file_size - f.tell() <= CHUNK_SIZE:
        dbx.files_upload_session_finish(f.read(CHUNK_SIZE), cursor, commit)
        break
    else:
        dbx.files_upload_session_append_v2(f.read(CHUNK_SIZE), cursor)
        cursor.offset = f.tell()
f.close()
END