I’d recommend using boto. Then it’s a quick couple of lines of python:
from boto.s3.connection import S3Connection
conn = S3Connection('access-key','secret-access-key')
bucket = conn.get_bucket('bucket')
for key in bucket.list():
print(key.name.encode('utf-8'))
Save this as list.py, open a terminal, and then run:
$ python list.py > results.txt