By default in the terminal interface expressions are printed in
OutputForm is an approximation to StandardForm which uses only ordinary keyboard characters.
As you observe this multi-line pseudo-2D output cannot (easily) be used as input.
InputForm formats expressions in a way that can be input to Mathematica:
InputForm always produces one-dimensional output, suitable to be typed as lines of Wolfram Language input.
However there is absolutely no certainty that this output can be used unmodified as input to other applications. This is why you see e.g.
1.234*^-9 -- that is valid Mathematica syntax.
There is no output format which is both compatible with other applications and which is capable of handling all expression types, so you will need to specify more clearly the output you are creating and the application that it is for. Some possibly useful functions: