Is there a way to find all files that are older than 100 days in one S3 bucket and move them to a different bucket? Solutions using AWS CLI or SDK both welcome.
In the src bucket, the files are organized like bucket/type/year/month/day/hour/file
S3://my-logs-bucket/logtype/2020/04/30/16/logfile.csv
For instance, on 2020/04/30, log files on or before 2020/01/21 will have to be moved.
As mentioned in my comments you can create a lifecycle policy for an S3 bucket. Here is steps to do it https://docs.aws.amazon.com/AmazonS3/latest/user-guide/create-lifecycle.html
It's optional to delete\expire an object using Lifecycle policy rules, you define the actions you want on the objects in your S3 bucket.
Lifecycle policies uses different storage classes to transition your objects. Before configuring Lifecycle policies I suggest reading up on the different storage classes as each have their own associated cost: Standard-IA, One Zone-IA, Glacier, and Deep Archive storage classes
Your use case of 100 days, I recommend transitioning your logs to a archive storage class such as S3 Glacier. This might prove to be more cost effective.