How to use s3cmd with AWS IAM Roles

S3Cmd is probably the easiest go to tool for command line s3 transfers.
This is how you use it with AWS IAM Roles:
First install s3cmd using pip, install pip if it’s not already installed:
apt-get install python-pip
or
yum install python-pip
Next install the latest version available to pip, this is listed on the s3cmd PyPi page:
At the time of writing, the latest s3cmd version in PyPi is 1.5.0-alpha3, so install by using the exact version:
pip install s3cmd==1.5.0-alpha3
By default with pip install (at least on Ubuntu 14.04), you’ll only get version 1.0.1 which doesn’t handle IAM Roles. This is why you need to specify the latest version in the install.
Alternatively you could get the very latest version and install manually without pip if the pip version is lagging behind:
Now just create a ~/.s3cfg config with blank values to make s3cmd detect and use your IAM Role that you’ve assigned to your EC2 instance:
[default]
access_key =
secret_key = 
security_token =
Now test it out:
s3cmd ls s3://bucket-you-should-have-access-to