Runs an arbitrary command within a bash session in which a temporary ssh-agent is running

0-usage

$ DEBUG=1 ./vaulted-bash.sh bash
Starting ssh-agent...
Started ssh-agent
Type path to ssh key. Blank to continue> /Users/example/.ssh/id_rsa
Identity added: /Users/example/.ssh/id_rsa (/Users/example/.ssh/id_rsa)
Type path to ssh key. Blank to continue>
bash-3.2$ ssh-add -l
4096 SHA256:PXeBU/YU3qFCpTIQvE5HHVwa8tnaftJzgNukHswTJrc /Users/example/.ssh/id_rsa (RSA)
bash-3.2$ exit
exit
Stopped ssh-agent(80564)

1-run-with-temp-ssh-agent.sh

# Place this in your .bash_profile for interactive-only support, 
# or in .bashrc for interactive and non-interactive support.
#
# See: https://confluence.atlassian.com/display/BITBUCKET/Set+up+SSH+for+Git#SetupSSHforGit-installpublickey

SSH_ENV="$HOME/.ssh/environment"

debug() {
  if [ ! -z "$DEBUG" ]; then
      echo "$1"
  fi
}

on_exit() {
  :
}

before_exit() {
  debug "Stopping ssh-agent($SSH_AGENT_PID)"
  kill $SSH_AGENT_PID
  while ps -p $SSH_AGENT_PID >/dev/null; do
    debug "."
    sleep 1
  done
  debug "Stopped ssh-agent($SSH_AGENT_PID)"
  exit 2
}

trap on_exit EXIT                           # EXIT = 0
trap before_exit HUP INT QUIT TERM STOP  # 1 2 3 15
  
# start the ssh-agent
function start_agent {
    debug  "Starting ssh-agent..."
    # spawn ssh-agent
    ssh-agent | sed 's/^echo/#echo/' > "$SSH_ENV"
    debug "Started ssh-agent"
    chmod 600 "$SSH_ENV"
    . "$SSH_ENV" > /dev/null

    while debug "Type path to ssh key. Blank to continue> " && read SSH_KEY; do
      if [ -z "$SSH_KEY" ]; then
        break
      fi
      msg=$(ssh-add $SSH_KEY 2>&1)
      debug "$msg"
    done
}
  
# test for identities
function test_identities {
    ssh-add -l | grep "The agent has no identities" > /dev/null
}

# check for running ssh-agent with proper $SSH_AGENT_PID
if [ -n "$SSH_AGENT_PID" ]; then
    ps -ef | grep "$SSH_AGENT_PID" | grep ssh-agent > /dev/null
    if [ $? -eq 0 ]; then
    test_identities
    fi
# if $SSH_AGENT_PID is not properly set, we might be able to load one from
# $SSH_ENV
else
    unset SSH_AUTH_SOCK
    unset SSH_AGENT_PID
    start_agent
    test_identities
fi

"$@"

# For handling Ctrl-D (if `stty -a` outputs `eof = ^D`)
before_exit

2-possible-alternative-simpler-impl.sh

#!/usr/bin/env bash

# Usage:
#   $ mkfifo p1
#   $ SSH_KEYS=p1 ./vaulted-bash-2.sh
#   # In another shell:
#   $ echo $HOME/.ssh/id_rsa $another_key > p1
#   $ ls p1 # not found

set -e

if [ -z "$SSH_KEYS" ]; then
  echo "SSH_KEYS must not be empty" 1>&2
  exit 2
fi

cleanup() {
  if [ -e "$SSH_KEYS" ]; then
    rm "$SSH_KEYS"
  fi
  exit 2
}

trap cleanup EXIT

ssh-agent bash -ic 'while read path; do echo $path && ssh-add $path; done <"$SSH_KEYS" && rm "$SSH_KEYS" && bash'