How to use return value of one program as input for another?

Question

I know that I can use pipes to set the output stream of one program to input for another:

bigNumber | factors

But what if I want to simply feed the returned value from bigNumber 's main function as factors 's input rather than what bigNumber echos to the output stream?

Answer 1

Try this:

bigNumber
echo $? | factors

Most Unix/Linux shells make the exit value available in the variable $? .

Answer 2

The error code returned by the last executed program is available in the $? shell variable