How to pass an "enter" to the external application?

Question

I have been trying to make an .exe file that I have become more automated by using Mathematica, but I am having trouble getting it to work. The file is based in command prompt and I basically need to do:

1. Open program
2. enter string
3. press enter key
4. enter string
5. press enter key
6. enter string
7. press enter key
8. press enter key

I do not need any of the output from the program since it is making a new txt file for me which I will read separately. I do not know how to go about "pressing the enter key" or even inputting the string I need to. I can get Mathematica to open the file with SystemOpen[], but I can not get it to enter anything through Mathematica itself. Let me know if you need anymore clarification!

Answer 1

See the manual for StartProcess. With a small adaptation to the example given there you should be able to achieve the goal.

Just an example application

pathtoexe = "echo";

Opens a stream, which in Mathematica is called ProcessObject

process = StartProcess[pathtoexe]

Writes three lines to a standard input:

WriteLine[process, "write string one"];
WriteLine[process, "write string two"];
WriteLine[process, "write string three"];

Note, that each time WriteLine by default already adds the "enter" as a hidden linefeed character \n. Thus, if you just need an extra "enter" in the end, just send a empty string once more:

WriteLine[process, ""];

Close the process, if it already has not stopped:

KillProcess[process]

If this does not solve your problem, then please extend your question with a more specific example, such that we could run the same code as you and help you more efficiently.