How to read mutliline input from stdin into variable and how to print one out in shell(sh,bash)?

Question

What I want to do is the following:

1. read in multiple line input from stdin into variable A
2. make various operations on

Answer 1

If you do care about preserving trailing newlines at the end of the output, use this:

myVar=$(cat; echo x)
myVar=${myVar%x}
printf %s "$myVar"

This uses the trick from here.