Portage log

When using for building a package, it is not uncommon to notice messages coming from Portage itself. Since they may contain important information from Gentoo developers it is a good idea to read them, but often this is not immediately possible because they rapidly scroll out of the screen. This can be easily solved by enabling a Portage feature called elog, whose purpose is to save messages to disk for later review. But other logging capabilities exist as well...

Portage elog subsystem
The Portage elog subsystem keeps track of specific, ebuild-provided log messages that developers have put in the ebuilds to attract attention of the administrator or user. Often, these messages contain important or interesting information related to the build of said package.

Setup
Select which kind of information should be logged through the PORTAGE_ELOG_CLASSES variable. Possible values are,  ,  ,  , and  :

Configuring for file-based storage
Portage can handle the elog events in a number of ways.

In order to save the elog events to disk, enable the  module in the PORTAGE_ELOG_SYSTEM variable:

The messages will be saved in or in  if said variable is set.

In order to create per-category elog files, enable the  Portage feature. It will force Portage to create category-based subdirectories of the location.

Configuring for e-mail
To mail logs to a recipient, enable the  module. The mail option requires some additional variables to be set. Read for more information.

Below, an example setup is shown which is hopefully self-explanatory:

Another example with nullmailer or sendmail:

Related software
The following is a list of elog-related software packages:


 * - Curses based utility to parse the contents of elogs
 * - Python based elog viewer

Build logs
Package build logs can be saved to disk or mailed to a remote recipient. This allows administrators to review builds later.

Setup
To enable saving build logs, edit and set PORTAGE_LOGDIR to a location where the log files should be stored. By default, when is running, Portage saves the build log of a package to  (possibly followed by an extension if   is in FEATURES ), where PORTAGE_TMPDIR is  unless set to something different in, and ${CATEGORY} and ${PF} represent the package's category and name (with version and revision), respectively. Directory will be deleted after  finishes successfully, and the contained build log lost, but kept if it doesn't, so the log will still be available for attaching to support tickets:

It is customary to choose as the location for log files, because it is where the elog subsystem's  directory would be if PORTAGE_LOGDIR has been previously empty or unset.

Next, you may want to edit and/or set a number of FEATURES= settings in  which influence how Portage handles build logs.


 * With  set, even binary package deployments will have their logs saved
 * When  is set, regular log file clean operations are executed. The command that is executed is defined by PORTAGE_LOGDIR_CLEAN and defaults to a retention of the files of 7 days.
 * With  set, build logs are stored in category-named subdirectories of

Cleaning up
When  is set, Portage will execute the command defined by PORTAGE_LOGDIR_CLEAN after every build or unmerge operation. By default, the following command is used:

When defining a custom command, do not forget to escape the PORTAGE_LOGDIR variable (or immediately hardcode the right location).

External resources

 * Sven Vermeulen. "Underestimated or underused: Portage (e)logging ", September 25th, 2013. Retrieved on May 30th, 2019.