This python example searches for the oldest file in a bucket and prints same.

Ensure to pip install boto3

import boto3

# Specify the bucket name
bucket_name = 'my-bucket'

s3 = boto3.resource('s3')

bucket = s3.Bucket(bucket_name)

# Initialize oldest_file and oldest_date to None
oldest_file = None
oldest_date = None

# Iterate through all files in the bucket
for obj in bucket.objects.all():
    # If oldest_file is None, or this file was modified before the oldest file
    # then update oldest_file and oldest_date to this file's name and last_modified date
    if oldest_file is None or obj.last_modified < oldest_date:
        oldest_file = obj.key
        oldest_date = obj.last_modified

# Print the oldest file's name and its last_modified date
if oldest_file is not None:
    print('The oldest file is {0} and was last modified on {1}'.format(oldest_file, oldest_date))
else:
    print('No files in bucket')