Replace old AWSume for Bash with new AWSume for Bash

[mbarneyjr]

AWSume for Bash

I recreated the AWSume script for Bash, starting from scratch, but referencing the old AWSume script for Bash. It now works more like the AWSume PowerShell script, but Linux friendly.

This script is more modular, emulating the PowerShell script.

There are three command-line options this script accepts: -s, -r, and -d:

• -s displays, to the console, the commands required to assume the role just assumed by the script.
• -r will refresh the session no matter what. The user will have to enter their MFA code even if they just used the script on the same profile.
• -d will assume the role of the default profile.

It is used in a similar fashion to the PowerShell script, too. To use this script, awsume [ profile_name ] [ flags ]

[mbarneyjr]

AWSume for Bash

• Added the prefix AWSUME_ to all variables, since the user will have to run this script sourced, we don't want any variable interference with any other possible running scripts.
• Brought most of the functions out to the main body of the script, to make it both easier to read and more efficient. This also allows easy escape out of the script with the return command, since you won't be returning from a function, you will return from the script, and not exit the terminal itself.
• Used a better method of getting the credentials from the aws sts get-session-token command by using the --query option and treating AWSUME_SessionText as an array, so that the script looks cleaner.
• The script will now remove a cache file if it is no longer valid or expired.
• Consolidated a few aws configure get commands, as they are slow and take up a lot of time.