How do you enter something at a console prompt programmatically?

Question

I have program, that must interact with a console program before my program can continue what it is doing. I'm trying to avoid my user from having to interact with this dos program. So, I created a .bat file that does everything I need to do except for the last step which still requires user interaction that I'm trying to avoid.

Specifically, the command I type ends up at a prompt where I need to automatically enter y and then Enter (to say yes to the prompt) and then I want to exit out.

Is there any way that I can make this happen automatically without my user having to enter y and Enter? Ideally, I'd like to have the console window NOT even pop up while this is going on.

Flatfoot

I'm not sure I understand how far you've come so far. Are you able to start this command that's prompting for "y"? How are you accomplishing that? What platform are you using? What language? C# with .NET? Java? – Vineyard

and the y <enter> isn't in the bat file because? – Reorientation

Austin, how do you do that? Just put "y <enter>" on the last line of the .bat file? – Flatfoot

Answer 1

You can pipe in a 'y' character into the program like so:

echo y | executable.exe

Multiple lines can be entered like so:

(echo y
echo n) | executable.exe

...which will pass first 'y' then 'n'.

See tip from Microsoft here.

Reconstructive

How does it know when to enter the y, when you pipe like this? – Flatfoot

It doesn't, it just sits in the buffer until the program asks for input – Roark

James, that worked. The script crashes, but not before it does the work I need done. Thanks. – Flatfoot

What do you do when you want to pass more than one command in? – Flatfoot

James, in my case, after the "y" comes a username prompt follows. But, at that point, I'd like to exit out instead of entering the username and password, because after the "y" is entered, the needed work is accomplished. Is there any way to pass a 2nd command that will make the console exit even though, that at that point, it is at another prompt that doesn't expect such a command? – Flatfoot

You might be able to echo in the Ctrl+C ascii character - (\x03) - but I'm trying it now on an exe that should break, and it's not. An alternate approach could be to host/monitor your application in another executable. There are capabilities for this in .NET using System.Diagnositics.Proceess - check out this article for some VB-based examples thescarms.com/dotnet/Process.aspx . Using that approach, you could monitor StandardOutput, wait for the prompt, enter 'y', and then terminate the application. – Reconstructive

It works fine when I try with a simple test, however if I try to echo a password to the rsync prompt (cygwin), it doesn't work. I haven't figured out why yet. – Fitzpatrick

You must remove the space in between echo y and | in order not to echo out such too… – Fireball

When I pass multiple inputs (with ()), a space is appended after first input. why? – Ferret

Answer 2

The post from Microsoft also clearly says :

Do not type a space between the "y" and the pipe symbol (|)

and indeed, I noticed that in my case

echo y | executable.exe

doesn't work while

echo y| executable.exe

works fine

Meshach

This is more like a comment instead of answer to an original question. – Cule

This comment looks way better as an answer (because of the formatting allowed in answers that are not allowed in comments). I'm glad he made it an answer instead of a comment for that reason. – Flatfoot

…though this is "more correct" than the accepted answer… – Fireball

Answer 3

I used the following, since "echo y | executable.exe" didn't worked for me

// Write a "Y" to the process's input
proc.StandardInput.WriteLine("Y");
// Now that we've sent the confirmation "Y" wait for the process to exit
proc.WaitForExit();

as posted here: https://www.experts-exchange.com/questions/27024185/C-ProcessStart-How-to-automatically-press-the-Y-key.html

Brendon