Today I had to verify a patch that I pushed upstream but which was slightly modified. As I don't use the tool myself (it was a user-reported issue) I decided to quickly drum up a live ebuild for the application and install it (as the patch was in the upstream repository but not in a release yet). The patch is for fcron's SELinux support, so the file I created is fcron-9999.ebuild.

Sadly, the build failed at the documentation generation (something about "No targets to create en/HTML/index.html"). That's unfortunate, because that means I'm not going to ask to push the live ebuild to the Portage tree itself (yet). But as my primary focus is to validate the patch (and not create a live ebuild) I want to ignore this error and go on. I don't need the fcron documentation right now, so how about I just continue?

To do so, I start using the ebuild command. As the failure occurred in the build phase (compile) and at the end (documentation was the last step), I tell Portage that it should assume the build has completed:

~# touch /var/portage/portage/sys-process/fcron-9999/.compiled

Then I tell Portage to install the (built) files into the images/ directory:

~# ebuild /home/swift/dev/gentoo.overlay/sys-process/fcron/fcron-9999.ebuild install

The installation phase fails again (with the same error as during the build, which is logical as the Makefile can't install files that haven't been properly build yet.) As documentation is the last step, I tell Portage to assume the installation phase has completed as well, continuing with the merging of the files to the life file system:

~# touch /var/portage/portage/sys-process/fcron-9999/.installed
~# ebuild /home/swift/dev/gentoo.overlay/sys-process/fcron/fcron-9999.ebuild qmerge

Et voila, fcron-9999 is now installed on the system, ready to validate the patch I had to check.