Handy helper script to generate new SSH keys in a predictable format, provide the needed ssh_config stanza to use them, and automatically upload them to the remote server.

ssh-mkkey

#!/usr/bin/env bash
#
# Handy helper script to generate new SSH keys in a predictable format,
# provide the needed ssh_config stanza to use them, and automatically
# upload them to the remote server.
#
# Copyleft 2014 Ian Gallagher <crash@neg9.org>

if [ -z "$1" ]; then
	echo "Usage: $0 <remote_host> [key_type] [key_size]" >&2
	exit 1
fi

host="$1"
type="$2"
size="$3"

if [[ -z $type ]]; then
	type="ed25519"
fi

if [[ -z $size ]]; then
	size="1000"
fi

remote_host=$(echo "$host" | tr 'A-Z' 'a-z')
local_host=$(hostname -s | tr 'A-Z' 'a-z')
year_date=$(date '+%Y-%m')

filename="id_${type}-${USER}-${remote_host}"
comment="${USER}-${local_host}-${remote_host}-${year_date}"
private_key="~/.ssh/${filename}"
public_key="${private_key}.pub"

# Create files with 0600 permissions
umask 077

# Use eval here so we can use tilde (~) in the variable and display it w/o expanding. eval expands for execution.
eval "ssh-keygen -t $type -b $size -f $private_key -C $comment"

if [ $? -eq 0 ]; then
	upload_key="ssh $remote_host 'cat >> .ssh/authorized_keys' < $public_key"
	echo "ssh_config entry:"
	echo "Host $remote_host"
	echo -e "\tIdentityFile $private_key"
	echo
	echo "Upload key to remote server: $upload_key"
	echo -n "Run above command now? (y/n): "
	read doit
	if [ "y" == "$doit" ]; then
		sh -c "$upload_key"
	fi

	exit 0
else
	echo "Failed to create new SSH keypair." >&2
	exit 1
fi

I wrote and tested this on OSX, but I think it should work on any *nix system. The date command may need tweaking in some situations though.