.bashrc

# Place this command in your .bashrc (or whatever is appropriate for your shell of choice).
alias aws='client=$1 source ~/bin/aws.sh $client'

aws.sh

#!/bin/bash
# Create this file as "~/bin/aws.sh"
export EC2_REGION='us-east-1' # Set default region
case "$1" in
"rbn") 
   export AWS_ACCESS_KEY='AKKDHH2HVQSHVQ32A'
   export AWS_SECRET_KEY='vizCQvkKhmMioAP/BXSe4HANGh47azvAF'
   export AWS_ACCOUNT='RBN'
   ;;
"gl") 
   export AWS_ACCESS_KEY='AKIADFGDFHHTP7ELQ'
   export AWS_SECRET_KEY='Ty+mNit235235235ETiJY/rEfxJwbQ2h+b'
   export EC2_REGION='us-west-1' # Override default region
   export AWS_ACCOUNT='AnotherCompanyA'
   ;;
"mcg") 
   export AWS_ACCESS_KEY='AKIAJKA2F5KRZQDBZS7A'
   export AWS_SECRET_KEY='tuQIiXgHY0B3nTEy6WaUzTsZwHUg1DiJtlAb'
   export AWS_ACCOUNT='AnotherCompanyB'
   ;;
*) 
   export AWS_ACCOUNT="No account"
   ;;
esac
echo "$AWS_ACCOUNT is active."