You probably have access to a bunch of aws accounts, because you are a working stiff that supports everybodies silly aws hosted websites. No probs, have multiple profiles
List profiles: aws configure list-profiles
To add one, edit ~/.aws/credentials Add each profile like this:
[default]
aws_access_key_id=AKIAIOSFODNN7EXAMPLE
aws_secret_access_key=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY
[user1]
aws_access_key_id=AKIAI44QH8DHBEXAMPLE
aws_secret_access_key=je7MtGbClwBF/2Zp9Utk/h3yCo8nvbEXAMPLEKEY
Edit the ~/.aws/config file:
[profile user1]
region=us-east-1
output=text
To use the profile, just add --profile user1 to a command.
Sync Bucket to local (take a backup)
aws s3 sync s3://ya-bucket ./ya-bucket-bk --profile profile-name
To upload stuff, reverse the order of the locations, ie:
aws s3 sync ./ya-bucket-bk s3://ya-bucket --profile profile-name