Portage is Gentoo's default package manager. This post isn't supposed to be a tutorial, the handbook does a pretty good job of that already. I'm just recording a few tricks so I don't forget them.

User patches

While playing around with LDAP, I was trying to troubleshoot the SASL_NOCANON handling. “Gee,” I thought, “wouldn't it be nice to be able to add debugging printfs to figure out what was happening?” Unfortunately, I had trouble getting ldapwhoami working when I compiled it by hand. “Grrr,” I though, “I just want to add a simple patch and do whatever the ebuild already does.” This is actually pretty easy to do, once you're looking in the right places.

Write your patch

I'm not going to cover that here.

Place your patch where epatch_user will find it

This would be under


If your ebuild already calls epatch_user, or it uses an eclass like base that calls epatch_user internally, you're done. If not, read on…

Forcing epatch_user

While you could always write an overlay with an improved ebuild, a quicker fix for this kind of hack is /etc/portage/bashrc. I used:

if [ "${EBUILD_PHASE}" == "prepare" ]; then
    echo ":: Calling epatch_user";
    pushd "${S}"

to insert my patches at the beginning of the prepare phase.

Cleaning up

It's safe to call epatch_user multiple times, so you can leave this setup in place if you like. However, you might run into problems if you touch autoconf files, so you may want to move your bashrc somewhere else until you need it again!