Using yubikey 4c on Mac OS X (running Sierra)

.bash_profile

GPG_ENV=$( gpg-agent --daemon 2>/dev/null )
if [ $? == 0 ]; then
    eval $GPG_ENV
else
    export SSH_AUTH_SOCK=$(gpgconf --list-dirs agent-ssh-socket)
fi
export GPG_TTY=$(tty)

function copy-code() {
  echo $1 |sed -e 's/[^ ]* //' |pbcopy
}

# Create an alias for each oauth credential you have.
alias awscode='copy-code "$(ykman oath code aws-oauth-credential-name)"'

function aws-code() {
  ykman oath code envato-aws-users |sed -e 's/[^ ]* //'
}

# create an alias for each amazon account you login to
alias login-aws-admin='aws-vault login -t "$(aws-code)" aws-administrator'

brew software

brew install gnupg swig pinentry-mac
pip install yubikey-manager

gpg-agent.conf

pinentry-program /usr/local/bin/pinentry-mac
enable-ssh-support
default-cache-ttl 600
max-cache-ttl 7200