What does `apt-get -b source ` do exactly?

Question

It downloads source and patches, then what ? How can someone build the downloaded source just as the apt-get does manually ?

Answer 1

apt-get -b alone doesn't do anything, it has to be used in conjunction with two other options.

1. Run sudo apt-get build-dep <prog_name> to build dependencies for the program first
2. Run sudo apt-get -b source <prog_name> to actually download the source code and build it.

In my test just now with nano text editor, after running sudo apt-get build-dep nano and then sudo apt-get -b source nano, apt actually ran make file to compile all *.c source files and then deb-buildpackage to actually build the deb package for installation.