agentrc

#!/bin/env bash

#shellcheck source=/dev/null
#shellcheck disable=SC2012

# Track agent state in a host-specific file, in case we're using a shared filesystem across
# multiple machines.
SSH_AGENT_FILE=$HOME/.ssh/agent.${HOSTNAME}

# If there's a forwarded agent, it gets precedent. If there's not a forwarded agent, check for an
# existing ssh-agent env file.
if ! [[ -S "${SSH_AUTH_SOCK}" ]]; then
  [[ -f "${SSH_AGENT_FILE}" ]] && . "${SSH_AGENT_FILE}" 1>/dev/null
fi

if [[ -z ${SSH_AGENT_PID} ]]; then
  ssh_agent="ip: $(echo "${SSH_CONNECTION}" | awk '{print $1}')"
else
  ssh_agent="pid: ${SSH_AGENT_PID}"
fi

##########
# Determine which agent is active.
agent() {
  if [[ -z ${SSH_AGENT_PID} ]]; then
    ssh_agent="ip: $(echo "${SSH_CONNECTION}" | awk '{print $1}')"
  else
    ssh_agent="pid: ${SSH_AGENT_PID}"
  fi
  ssh-add -l
}

##########
# Update to a new forwarded agent. Sometimes old SSH sessions will have an outdated socket; this
# will use the freshest one.
agent-update() {
  sock="$(ls -1tr /tmp/ssh-*/* | tail -n1 2>/dev/null)"
  if [[ ! -S ${sock} ]]; then
    echo "No SSH socket found."
    return 1
  fi
  SSH_AUTH_SOCK="$(ls -1tr /tmp/ssh-*/* | tail -n1 2>/dev/null)"
  export SSH_AUTH_SOCK
  ssh-add -l
}

ssh-add -l &>/dev/null

case "$?" in
  0)
    ssh-add -l
    ;;
  1)
    echo "ssh-agent (${ssh_agent}) has no identities."
    ssh-add
    ;;
  *)
    if ! ([ -S "${SSH_AUTH_SOCK}" ] && kill -0 "${SSH_AGENT_PID}"); then
      echo "Starting new ssh-agent."
      mkdir -p $(dirname ${SSH_AGENT_FILE})
      ssh-agent > "${SSH_AGENT_FILE}"
      . "${SSH_AGENT_FILE}" >/dev/null
      ssh-add
      source "${BASH_SOURCE[0]}"
    fi
esac