Handbook:Parts/Portage/Files/en

Configuration directives
Portage comes with a default configuration stored in. All Portage configuration is handled through variables. What variables portage listens to and what they mean are described later.

Since many configuration directives differ between architectures, Portage also has default configuration files which are part of the system profile. This profile is pointed to by the symlink; Portage's configurations are set in the  files of the profile and all parent profiles. We'll explain more about profiles and the directory later on.

When changing a configuration variable, do not alter or. Instead use which has precedence over the previous files. For more information, read the. As the name implies, this is merely an example file - Portage does not read in this file.

It is also possible to define a Portage configuration variable as an environment variable, but we don't recommend this.

Profile-specific information
We've already encountered the directory. Well, this is not exactly a directory but a symbolic link to a profile, by default one inside although one can create their own profiles elsewhere and point to them. The profile this symlink points to is the profile to which the system adheres.

A profile contains architecture-specific information for Portage, such as a list of packages that belong to the system corresponding with that profile, a list of packages that don't work (or are masked-out) for that profile, etc.

User-specific configuration
When Portage's behavior needs to be changed regarding the installation of software, then the right set of files inside will need to be changed. It is highly recommended to use files within and highly discouraged to override the behavior through environment variables!

Within users can create the following files:
 * which lists the packages that Portage should never try to install
 * which lists the packages Portage should be able to install even though the Gentoo developers highly discourage users from emerging them
 * which lists the packages Portage should be able to install even though the package hasn't been found suitable for the system or architecture (yet)
 * which lists the USE flags to use for certain packages without having the entire system use those USE flags

These don't have to be files; they can also be directories that contain one file per package. More information about the directory and a full list of possible files that can be created can be found in the Portage man page:

Changing Portage file and directory locations
The previously mentioned configuration files cannot be stored elsewhere - Portage will always look for those configuration files at those exact locations. However, Portage uses many other locations for various purposes: build directory, source code storage, Gentoo repository location, ...

All these purposes have well-known default locations but can be altered to personal taste through. The rest of this chapter explains what special-purpose locations Portage uses and how to alter their placement on the filesystem.

This document isn't meant to be used as a reference though. To get 100% coverage, please consult the Portage and make.conf man pages:

Gentoo repository
The default location of the Gentoo ebuild repository is at. This is defined by the default file found at. To modify the default, copy this file to and change the location setting. When storing the Gentoo ebuild repository elsewhere (by altering this variable), don't forget to change the symbolic link accordingly.

After changing the location setting in, it is recommended to alter the following variables in as well since they will not notice the  location change. This is due to how Portage handles variables: PKGDIR, DISTDIR , and RPMDIR.

Prebuilt binaries
Even though Portage doesn't use prebuilt binaries by default, it has extensive support for them. When asking Portage to work with prebuilt packages, it will look for them in. This location is defined by the PKGDIR variable.

Source code
Application source code is stored in by default. This location is defined by the DISTDIR variable.

Portage database
Portage stores the state of the system (what packages are installed, what files belong to which package, ...) in.

Portage cache
The Portage cache (with modification times, virtuals, dependency tree information, ...) is stored in. This location really is a cache: users can clean it if they are not running any Portage-related application at that moment.

Temporary portage files
Portage's temporary files are stored in by default. This is defined by the PORTAGE_TMPDIR variable.

Building directory
Portage creates specific build directories for each package it emerges inside. This location is defined by the BUILD_PREFIX variable.

Live filesystem location
By default Portage installs all files on the current filesystem, but this can be changed by setting the ROOT environment variable. This is useful when creating new build images.

Ebuild logging
Portage can create per-ebuild log files, but only when the PORT_LOGDIR variable is set to a location that is writable by Portage (through the Portage user). By default this variable is unset. If PORT_LOGDIR is not set, then there will not be any build logs with the current logging system, though users may receive some logs from the new support.

If PORT_LOGDIR is not defined and is used, then build logs and any other logs saved by elog will be made available, as explained below.

Portage offers fine-grained control over logging through the use of elog:


 * PORTAGE_ELOG_CLASSES : This is where users can define what kinds of messages to be logged. This can be any space-separated combination of info, warn, error, log, and qa.
 * info: Logs "einfo" messages printed by an ebuild
 * warn: Logs "ewarn" messages printed by an ebuild
 * error: Logs "eerror" messages printed by an ebuild
 * log: Logs the "elog" messages found in some ebuilds
 * qa: Logs the "QA Notice" messages printed by an ebuild


 * PORTAGE_ELOG_SYSTEM : This selects the module(s) to process the log messages. If left empty, logging is disabled. Any space-separated combination of save, custom, syslog, mail, save_summary, and mail_summary can be used. At least one module must be used in order to use elog.
 * save: This saves one log per package in, or if $PORT_LOGDIR is not defined.
 * custom: Passes all messages to a user-defined command in $PORTAGE_ELOG_COMMAND; this will be discussed later.
 * syslog: Sends all messages to the installed system logger.
 * mail: Passes all messages to a user-defined mailserver in $PORTAGE_ELOG_MAILURI; this will be discussed later. The mail features of elog require >=portage-2.1.1.
 * save_summary: Similar to save, but it merges all messages in, or if $PORT_LOGDIR is not defined.
 * mail_summary: Similar to mail, but it sends all messages in a single mail when emerge exits.


 * PORTAGE_ELOG_COMMAND : This is only used when the custom module is enabled. Users can specify a command to process log messages. Note that the command can make use of two variables: ${PACKAGE} is the package name and version, while ${LOGFILE} is the absolute path to the logfile. For instance:


 * PORTAGE_ELOG_MAILURI : This contains settings for the mail module such as address, user, password, mail server, and port number. The default setting is "root@localhost localhost". The following is an example for an SMTP server that requires username and password-based authentication on a particular port (the default is port 25):


 * PORTAGE_ELOG_MAILFROM : Allows the user to set the "from" address of log mails; defaults to "Portage" if unset.


 * PORTAGE_ELOG_MAILSUBJECT : Allows the user to create a subject line for log mails. Note that it can make use of two variables: ${PACKAGE} will display the package name and version, while ${HOST} is the fully qualified domain name of the host Portage is running on. For instance: