Question

How can you set a string to be used instead of standard input? For example, when running the latex command in Unix it will always find some trivial errors, to skip through all errors you have to enter “r” into the command line (I now know that with latex specifically you can use -interactionmode nonstopmode, but is there a more general solution to do this?)
Is there anyway to specify that this should be done automatically? I tried redirecting standard input to read from a file containing “r\n”, but this didn’t work.
How can I achieve this?

Answer 1

Not all applications that need input can be satisfied with their stdin redirected.

This is because the app can call the isatty C function (if written in C, or some equivalent call for other languages) to determine if the input come from a tty or not.

In such situation, there is a valuable tool to use, and this is expect.