Update authorized keys on remote server using known_hosts

update-authorised-keys.sh

#!/usr/bin/env bash

# Before running remember to generate a new key and update this script with the name (currently id_rsa_4096.pub)

awk -F'[ ,:]' '/^[0-9a-zA-Z]/{sub(/\[/,"",$1); sub(/\]/,"",$1); print $1}' ~/.ssh/known_hosts | uniq > _hosts
# A script to push a key to the only argument, a remote server.
while read h; do
	
 	echo "$h"

	# Check if an argument was given.
	if [ ! "$h" ] ; then
	echo "Please specify a hostname to distribute the key to."
	exit 1
	fi

	# Check if all the local files are here.
	if [ ! -f ~/.ssh/id_rsa_4096.pub ] ; then
	echo "The local file ~/.ssh/id_rsa_4096.pub is missing!"
	exit 1
	fi

	# This command sends the key, create a .ssh dir if required and set the
	# correct permissions.
	cat ~/.ssh/id_rsa_4096.pub | ssh -l jack -o StrictHostKeyChecking=no -o ConnectTimeout=5 $h "if [ ! -d ~/.ssh/ ] ; then mkdir ~/.ssh ; fi ; chmod 700 ~/.ssh/ ; cat - >> ~/.ssh/authorized_keys ; chmod 600 ~/.ssh/authorized_keys"

done <_hosts

rm _hosts