Md at debian.org

ssh-agent for unattended processes

This code allows unattended ssh(1) processes, like the ones started by cron(8), to access the SSH keys stored by a running ssh-agent(1) (which will probably have been started in a screen(1) instance).

Be sure to understand the security implications of persistent ssh-agent processes and passwordless keys.

#!/bin/sh -e

import_ssh_agent() {
  local pid
  for pid in $(pgrep -u "$LOGNAME" -x -f /bin/bash); do
    local var="$(grep -z '^SSH_AUTH_SOCK=' /proc/$pid/environ || true)"
    [ "$var" ] || continue
    eval "$var"
    export SSH_AUTH_SOCK
    break
  done
}

[ "$SSH_AUTH_SOCK" ] || import_ssh_agent

# now the script can run commands like:
ssh -o BatchMode=yes hostname command