How to input automatically when running a shell over SSH?

Question

In my shell script I am running a command which is asking me for input.

How can I give the command the input it needs automatically?

For example:

$cat test.sh
ssh-copy-id tester@10.1.2.3

When running test.sh:

• First, it will ask:

  Are you sure you want to continue connecting (yes/no)?

• Then, it will ask me to input the password:

  tester@10.1.2.3's password:

Is there a way to input this automatically?

Answer 1

For simple input, like two prompts and two corresponding fixed responses, you could also use a "here document", the syntax of which looks like this:

test.sh <<!
y
pasword
!

The << prefixes a pattern, in this case '!'. Everything up to a line beginning with that pattern is interpreted as standard input. This approach is similar to the suggestion to pipe a multi-line echo into ssh, except that it saves the fork/exec of the echo command and I find it a bit more readable. The other advantage is that it uses built-in shell functionality so it doesn't depend on expect.