authenticate aws cli when mfa is enabled

aws_mfa.sh

#!/bin/bash

help () {
  echo 'Usage: sh aws_mfa.sh "$mfa_arn" $mfa_code';
  echo "\nWhere:"
  echo ' - $mfa_arn, is aws arn to the mfa device found in iam profile'
  echo ' - $mfa_code, is code generated by mfa device'
}

if [ "$1" == "-h" ] || [ "$1" == "--help" ]; then
  help
  exit 0
fi

arg1="${1%\"}" #trim suffix
arg1="${arg1#\"}" #trim prefix

# variables
_MFA_ARN=$arg1
_CODE=$2

aws sts get-session-token --serial-number "$_MFA_ARN" --token-code "$_CODE" \
    | jq '.Credentials | ("export AWS_ACCESS_KEY_ID=" + .AccessKeyId),("export AWS_SECRET_ACCESS_KEY=" + .SecretAccessKey),("export AWS_SESSION_TOKEN=" + .SessionToken)';