simple_pubkey_appender.sh

#! /bin/bash
#Assumptions
#Default user deploy whose SSH authorized_keys is to modify
#SSH authorized_keys is in the format ssh-rsa key 
home=${home:-deploy}
username=$1

#get public key from a github
KEY="https://github.com/$username.keys"
curl --silent $KEY -o /tmp/$username.pub

ssh_auth_file=`eval echo ~${home}/.ssh/authorized_keys`

##Append found keys to authorized_keys file
while read line
do
echo $line >> ${ssh_auth_file}
done <"/tmp/${username}.pub"

#Simulate idempotence/de-duplication
cat $ssh_auth_file | sort -u -k1,2 > ${ssh_auth_file}.uniq
mv ${ssh_auth_file}.uniq ${ssh_auth_file}