A Bash script to interchange multiple GitHub users in a unique machine

switch-github-user.sh

#!/bin/bash
gh_user="${1:-Nothing}"

if [ "$gh_user" == 'USERNAME_1' ]; then
  ssh-add -D
  git config --global user.email "USERNAME_1_EMAIL"
  ssh-add /PRIVATE_KEY_PATH/.ssh/github-USERNAME_1
elif [ "$gh_user" == 'USERNAME_2' ]; then
  ssh-add -D
  git config --global user.email "USERNAME_2_EMAIL"
  ssh-add /PRIVATE_KEY_PATH/.ssh/github-USERNAME_2
else
  echo 'Nothing was applied'
  exit 1
fi
echo "$gh_user applied!"
git config user.email
ssh -T git@github.com
exit 0

# TO USE 
# ./switch-github-user.sh USERNAME_1

Works great!