Preventing users from running mkdir in an S3 bucket

You can limit users' ability to create a directory in an Amazon S3 bucket. To do so, you create an IAM policy that allows the s3:PutObject action but also denies it when the key ends with a "/" (forward slash). The following example policy allows users to upload files to an Amazon S3 bucket but denies the mkdir command in the Amazon S3 bucket.

{
   "Sid":"DenyMkdir",
   "Action":[
      "s3:PutObject"
   ],
   "Effect":"Deny",
   "Resource":[
      "arn:aws:s3:::amzn-s3-demo-bucket/*/",
      "arn:aws:s3:::amzn-s3-demo-bucket/*/*"
    ]
}