在Bash中使用'expect'以及任何顺序的响应

Question

I'm using this expect file (keygen.exp) to generate SSH key, I'm using ssh-keygen just as example to test 'expect':

#!/usr/bin/expect
spawn ssh-keygen

expect "Enter file"
send "./id_rsa\r"

expect "Enter passphrase"
send "\r"

expect "Enter same passphrase"
send "\r"

interact

It works perfectly, however, what if the order of the prompts for inputs is not the same every run, and there might be different questions on different runs ?

I want something like this:

#!/usr/bin/expect
spawn ssh-keygen

expect if-is "Enter file"
send "./id_rsa\r"

expect if-is "Enter passphrase"
send "\r"

expect if-is "Enter same passphrase"
send "\r"

interact

Is it possible?

Answer 1

You can have single expect statement which loops, processing different outputs differently, something like:

expect {
  "Enter file" {
    send "./id_rsa\r"
    exp_continue
  }
  "Enter passphrase" {
    send "\r"
    exp_continue
  }
  "Enter same passphrase" {
    send "\r"
    exp_continue
  }
  $ 
}

But note that you need some way to break out of the loop. The last pattern here - $ has no exp_continue (or any other action) so it will break out of the loop if the prompt you get when logged in includes $ . See the full documentation at https://www.tcl.tk/man/expect5.31/expect.1.html

Answer 2

Expect in any order, with infinite timeout:

#!/usr/bin/expect
spawn /path/to/some-programme

expect {
  "some string" {
    set timeout -1
    send "some input\r"
    exp_continue
  }
  "some other string" {
    set timeout -1
    send "some other input\r"
    exp_continue
  }
  ...
}

#no 'interact'
#end of file