check_ssh_agent.sh

# Filename: check_ssh_agent.sh
#
# Description: Check if ssh-agent environment exists for the session and 
#              create it if it does not.
#              
# NOTE:
# Do not run this command directly, but import it in your .bashrc file with:
#
#   source /path/to/check_ssh_agent.sh
#
# Otherwise SSH_AGENT_PID and SSH_AUTH_SOCK environment variables are not set.
#
last_ssh_agent_file="${HOME}/.last_ssh_agent"
if [[ ! $SSH_AUTH_SOCK || \
      ! $SSH_AGENT_PID || \
      ! -e $SSH_AUTH_SOCK || \
      ! -e /proc/$SSH_AGENT_PID ]]
then
  if [[ -r $last_ssh_agent_file ]]
  then
    source "$last_ssh_agent_file" > /dev/null
  fi
fi
if [[ $SSH_AUTH_SOCK && \
      $SSH_AGENT_PID && \
      -e $SSH_AUTH_SOCK && \
      -e /proc/$SSH_AGENT_PID ]]
then
  true
  # echo "ssh-agent is present, details:"
  # echo "SSH_AUTH_SOCK=${SSH_AUTH_SOCK}"
  # echo "SSH_AGENT_PID=${SSH_AGENT_PID}"
else 
  unset SSH_AUTH_SOCK SSH_AGENT_PID
  echo "Starting ssh-agent..."
  ssh_agent=$(ssh-agent)
  if [[ $? == 0 ]]
  then
    echo "$ssh_agent" > "$last_ssh_agent_file"
    source "$last_ssh_agent_file" > /dev/null
    # echo "ssh-agent started, details:"
    # echo "SSH_AUTH_SOCK=${SSH_AUTH_SOCK}"
    # echo "SSH_AGENT_PID=${SSH_AGENT_PID}"
  else
    echo "Error: could not start ssh-agent" 1>&2
  fi
fi