On Wed, May 9, 2018 at 8:59 AM, Ugesh Reddy via bitbake-devel <bitbake-devel@lists.openembedded.org> wrote:
Hello,
 The devtool hides out the information and trying to learn bitbake and wanted understand each entry in the .BB files.So I would to write it instead of tool.

Could you guide me?

How to write a recipe is well documented:

  https://www.yoctoproject.org/docs/current/mega-manual/mega-manual.html#new-recipe-writing-a-new-recipe
  https://www.yoctoproject.org/docs/current/mega-manual/mega-manual.html#new-recipe-autotooled-package

You can also learn a lot by reviewing and understanding the recipes in oe-core.