Transfer files between Amazon EC2 and S3 [closed]

I have log files generated by my application running on EC2. I want to first upload the log file to a bucket in S3. I then run a map reduce job and I want to then download the output file back to EC2.

What is the best way for me to upload and download files from EC2 and S3? Is it possible to do automate the process using Shell script on EC2, given that I'm using a linux instance? Also, would I need to modify access permission on the s3 bucket?

Is data transfer between EC2 and S3 free?

Data transfers between AWS services which can't be confined to a particular Availability Zone or VPC (the clearest example being AWS S3) and EC2 instances or other AWS services within the same region are free.

This is another tool I'm using for s3: http://s3tools.org/s3cmd