How to make a batch file that send application an input char

I'm writing a batch file that launch an开发者_如何学C application.

app.exe

After the application is launched, I'm getting a list of options in the console, and the program waits for input, for example:

a: start session

b: end session

c: end

How do I make the batch type a?

Other than using echo as @npclaudiu suggested, you could also write the expected input to a text file and then have the app read the file:

app.exe <input.txt

This works if the app expects more than one line of input.

First, make sure if the application supports command line arguments. For example, at your command prompt, type:

C:\> app.exe /?

or

C:\> app.exe -h

or

C:\> app.exe --help

If it doesn't, try using

echo a | app.exe