part of .bash_profile on OS X that launches an instance of gpg-agent per console session

.bash_profile

# gpg-agent initialization

GPG_INFO_FILE=${HOME}/.gpg-agent-info

if [ -f "$GPG_INFO_FILE" ]; then
    source "$GPG_INFO_FILE"
fi

RUNNING_DAEMON=$(ps -p $SSH_AGENT_PID 2> /dev/null | tail -n+2 | grep gpg)

if [ "$RUNNING_DAEMON" == "" ]; then
    gpg-agent --daemon --enable-ssh-support --write-env-file "${HOME}/.gpg-agent-info"
fi

if [ -f "$GPG_INFO_FILE" ]; then
    source "$GPG_INFO_FILE"
    export GPG_AGENT_INFO
    export SSH_AUTH_SOCK
    export SSH_AGENT_PID
fi

export GPG_TTY=`tty`