Using expect for inputting commands

Question

Heres the thread I'm bouncing off of: Inputting input in a command?

So I'm trying to run this command: cd /etc/openvpn/easy-rsa; . ./vars; ./build-key username

However, after running that command, I need to input nothing [just press enter] 10 times, and press y twice. The user on the last thread suggested I use except, but I couldn't get it working. Here are the questions it asks:

root@suffice-vpn:/etc/openvpn/easy-rsa# ./build-key usernamtest
Generating a 2048 bit RSA private key
..................+++
........+++
writing new private key to 'usernamtest.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [US]:
State or Province Name (full name) [NY]:
Locality Name (eg, city) [Merrick]:
Organization Name (eg, company) [IceWare]:
Organizational Unit Name (eg, section) [IceWare]:
Common Name (eg, your name or your server's hostname) [usernamtest]:
Name [server]:
Email Address [[email protected]]:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /etc/openvpn/easy-rsa/openssl-1.0.0.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'US'
stateOrProvinceName   :PRINTABLE:'NY'
localityName          :PRINTABLE:'Merrick'
organizationName      :PRINTABLE:'IceWare'
organizationalUnitName:PRINTABLE:'IceWare'
commonName            :PRINTABLE:'usernamtest'
name                  :PRINTABLE:'server'
emailAddress          :IA5STRING:'[email protected]'
Certificate is to be certified until Jan 14 18:27:48 2026 GMT (3650 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y

As you can see, I press enter 8 times initially [to keep the default input] and then press enter another 2 times to skip the optional commands. Then, I need to press y twice. How can I automate this? I need to have this all happen in one command. Any suggestions? Thanks in advance.

Answer 1

Here's a quick'n'dirty expect script that you can try (I can't test it myself, since I'm not using openvpn anywhere):

#!/usr/bin/expect

set timeout 20
set username [lindex $argv 0]

spawn ./build-key $username

while 1 { 
  expect { 
    "y/n]" { send "y\r" }
    "]:" { send "\r" }
    eof { break } 
  } 
}

It basically sends y whenever it sees a y/n] question and just a newline whenever it sees any other closing square bracket ], until it runs out of input.

You can save it as whatever, make it executable, and then execute

./whatever usernametest

Answer 2

I found an easier alternative:

cd /etc/openvpn/easy-rsa; . ./vars; ./build-key --batch username