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Exploring portage features

While most of them are documented in the example make.conf and the portage man page they may not be obvious to most users, so we will show how to use some of these features.

All the features have to be set in /etc/make.conf.

Portage is now able to download some package's source code while compiling another. This can considerably reduce installation time when emerging many packages. There's no need to run emerge --fetchonly while doing a normal emerge anymore. You just have to add the following option:

Code Listing 1:

Setting parallel-fetch in /etc/make.conf
FEATURES="parallel-fetch"

This feature appears to be non-functional in some of the Portage 2.1 releases, but is expected to be fixed soon.

Another new option to reduce installation time yet a bit more is confcache. With this new feature portage caches many of the tests configuration scripts do, thus making execution faster. This comes with the small risk of caching wrong values, so be warned that this feature is known to have a few bugs.

Since this package is currently keyworded on most architectures, the required steps to enable it are:

Code Listing 2

Enabling confcache
Add this in /etc/make.conf
FEATURES="confcache"

We need to unmask the package before emerging it

echo "=dev-utils/confcache-0.4.2-r1 ~arch" >>/etc/portage/package.keywords

Installing confcache

emerge -av confcache

On further installations. you'll see stuff like:

checking for i686-pc-linux-gnu-gcc... (cached) i686-pc-linux-gnu-gcc
checking whether we are using the GNU C compiler...(cached) yes
checking whether i686-pc-linux-gnu-gcc accepts -g... (cached) yes

Another important new feature is the ability to log all the messages ebuilds print. Which messages to log and how to do it is configurable. For example, to save just the warnings and errors in a separate file for each package we emerge, you have to add:

Code Listing 5.3:

Configuring logging features in /etc/make.conf
This sets what to log
PORTAGE_ELOG_CLASSES="warn error log"
And this is how to do it
PORTAGE_ELOG_SYSTEM="save"

There are many more options like sending log messages via email. Please check out make.conf.example for further information.

From Gentoo Weekly Newsletter June, 20th 2006

minor problem with confcache - it no longer seems to exist in the build tree unless perhaps it was renamed.