How to make ssh-add read passphrase from a file?

ssh ssh-agent
Satish picture Satish · Oct 23, 2012 · Viewed 34.4k times · Source

I am trying to add a key to ssh-agent and want ssh-add to read the password from the key file I'm using. How is this possible?

How do I automate this process from the shell script?

Answer

enrico.bacis picture enrico.bacis · Oct 23, 2012

Depending on your distribution and on the version of ssh-add you may be able or not to use the -p option of ssh-add that reads the passphrase from stdin in this way:

cat passfile | ssh-add -p keyfile

If this is not working you can use Expect, a Unix tool to make interactive applications non-interactive. You'll have to install it from your package manager.

I have written a tool for you in expect. Just copy the content in a file named ssh-add-pass and set executable permissions on it (chmod +x ssh-add-pass). You can also copy it to /usr/bin or /usr/local/bin to be accessible from the $PATH search.

#!/bin/bash

if [ $# -ne 2 ] ; then
  echo "Usage: ssh-add-pass keyfile passfile"
  exit 1
fi

eval $(ssh-agent)
pass=$(cat $2)

expect << EOF
  spawn ssh-add $1
  expect "Enter passphrase"
  send "$pass\r"
  expect eof
EOF

The usage is simply: ssh-add-pass keyfile passfile

Related questions

Could not open a connection to your authentication agent

I am running into this error of: $ git push heroku master Warning: Permanently added the RSA host key for IP address '50.19.85.132' to the list of known hosts. ! Your key with fingerprint b7:fd:15:25:02:8e:5f:06:4f:1c:af:…

Read More
How to permanently add a private key with ssh-add on Ubuntu?

I have a private key protected with a password to access a server via SSH. I have 2 linux (ubuntu 10.04) machines and the behavior of ssh-add command is different in both of them. In one machine, once I use "ssh-add .ssh/…

Read More
Start ssh-agent on login

I have a site as a remote Git repo pulling from Bitbucket.com using an SSH alias. I can manually start the ssh-agent on my server but I have to do this every time I login via SSH. I manually …

Read More