Contents

List of Algorithms

Listings

List of Tables

Acknowledgements

Thanks to Mike Kelly (package manager provided utilities, section 12.3.3), Danny van Dyk (ebuild functions, section 10), David Leverton (various sections), Petteri Räty (environment state, section 12.2) and Ulrich Müller (various sections) for contributions. Thanks to Christian Faulhammer for fixing some of the more horrible formatting screwups and providing the EAPI cheat sheet. Thanks also to Mike Frysinger and Brian Harring for proof-reading and suggestions for fixes and/or clarification.

Copyright and Licence

The bulk of this document is © 2007, 2008, 2009 Stephen Bennett and Ciaran McCreesh. Contributions are owned by their respective authors, and may have been changed substantially before inclusion.

This document is released under the Creative Commons Attribution-Share Alike 3.0 Licence. The full text of this licence can be found at http://creativecommons.org/licenses/by-sa/3.0/.

Reporting Issues

Issues (inaccuracies, wording problems, omissions etc.) in this document should be reported via Gentoo Bugzilla using product Gentoo Hosted Projects, component PMS/EAPI and the default assignee. There should be one bug per issue, and one issue per bug.

Patches (in git format-patch form if possible) may be submitted either via Bugzilla or to the gentoo-pms@gentoo.org mailing list. Patches will be reviewed by the PMS team, who will do one of the following:

• Accept and apply the patch.
• Explain why the patch cannot be applied as-is. The patch may then be updated and resubmitted if appropriate.
• Reject the patch outright.
• Take special action merited by the individual circumstances.

When reporting issues, remember that this document is not the appropriate place for pushing through changes to the tree or the package manager, except where those changes are bugs.

If any issue cannot be resolved by the PMS team, it may be escalated to the Gentoo Council.

Chapter 1
Introduction

1.1 Aims and Motivation

This document aims to fully describe the format of an ebuild repository and the ebuilds therein, as well as certain aspects of package manager behaviour required to support such a repository.

This document is not designed to be an introduction to ebuild development. Prior knowledge of ebuild creation and an understanding of how the package management system works is assumed; certain less familiar terms are explained in the Glossary in chapter 15.

This document does not specify any user or package manager configuration information.

1.2 Rationale

At present the only definition of what an ebuild can assume about its environment, and the only definition of what is valid in an ebuild, is the source code of the latest Portage release and a general consensus about which features are too new to assume availability. This has several drawbacks: not only is it impossible to change any aspect of Portage behaviour without verifying that nothing in the tree relies upon it, but if a new package manager should appear it becomes impossible to fully support such an ill-defined standard.

This document aims to address both of these concerns by defining almost all aspects of what an ebuild repository looks like, and how an ebuild is allowed to behave. Thus, both Portage and other package managers can change aspects of their behaviour not defined here without worry of incompatibilities with any particular repository.

1.3 Conventions

Text in teletype is used for filenames or variable names. Italic text is used for terms with a particular technical meaning in places where there may otherwise be ambiguity.

The term package manager is used throughout this document in a broad sense. Although some parts of this document are only relevant to fully featured package managers, many items are equally applicable to tools or other applications that interact with ebuilds or ebuild repositories.

Chapter 2
EAPIs

2.1 Definition

An EAPI can be thought of as a ‘version’ of this specification to which a package conforms. An EAPI value is a string, and is part of an ebuild’s metadata.

If a package manager encounters a package version with an unrecognised EAPI, it must not attempt to perform any operations upon it. It could, for example, ignore the package version entirely (although this can lead to user confusion), or it could mark the package version as masked. A package manager must not use any metadata generated from a package with an unrecognised EAPI.

The package manager must not attempt to perform any kind of comparison test other than equality upon EAPIs.

EAPIs are also used for profile directories, as described in section 5.2.2.

2.2 Defined EAPIs

The following EAPIs are defined by this specification:

0

The ‘original’ base EAPI.

1

EAPI ‘1’ contains a number of extensions to EAPI ‘0’. Except where explicitly noted, it is in all other ways identical to EAPI ‘0’.

2

EAPI ‘2’ contains a number of extensions to EAPI ‘1’. Except where explicitly noted, it is in all other ways identical to EAPI ‘1’.

3

EAPI ‘3’ contains a number of extensions to EAPI ‘2’. Except where explicitly noted, it is in all other ways identical to EAPI ‘2’.

4

EAPI ‘4’ contains a number of extensions to EAPI ‘3’. Except where explicitly noted, it is in all other ways identical to EAPI ‘3’.

Except where explicitly noted, everything in this specification applies to all of the above EAPIs.¹

2.3 Reserved EAPIs

• EAPIs whose value consists purely of an integer are reserved for future versions of this specification.
• EAPIs whose value starts with the string paludis- are reserved for experimental use by the Paludis package manager.

Chapter 3
Names and Versions

3.1 Restrictions upon Names

No name may be empty. Package managers must not impose fixed upper boundaries upon the length of any name. A package manager should indicate or reject any name that is invalid according to these rules.

3.1.1 Category Names

A category name may contain any of the characters [A-Za-z0-9+_.-]. It must not begin with a hyphen or a dot.

Note: A hyphen is not required because of the virtual category. Usually, however, category names will contain a hyphen.

3.1.2 Package Names

A package name may contain any of the characters [A-Za-z0-9+_-]. It must not begin with a hyphen, and must not end in a hyphen followed by one or more digits.

Note: A package name does not include the category. The term qualified package name is used where a category/package pair is meant.

3.1.3 Slot Names

A slot name may contain any of the characters [A-Za-z0-9+_.-]. It must not begin with a hyphen or a dot.

3.1.4 USE Flag Names

A USE flag name may contain any of the characters [A-Za-z0-9+_@-]. It must begin with an alphanumeric character. Underscores should be considered reserved for USE_EXPAND, as described in section 12.1.1.

Note: The at-sign is required for LINGUAS.

3.1.5 Repository Names

A repository name may contain any of the characters [A-Za-z0-9_-]. It must not begin with a hyphen.

3.1.6 Keyword Names

A keyword name may contain any of the characters [A-Za-z0-9_-]. It must not begin with a hyphen. In contexts where it makes sense to do so, a keyword name may be prefixed by a tilde or a hyphen. In KEYWORDS, -* is also acceptable as a keyword, to indicate that a package will only work on listed targets.

A tilde prefixed keyword is, by convention, used to indicate a less stable package. It is generally assumed that any user accepting keyword ~foo will also accept foo.

The exact meaning of any keywords value is beyond the scope of this specification.

3.2 Version Specifications

The package manager must not impose fixed limits upon the number of version components. Package managers should indicate or reject any version that is invalid according to these rules.

A version starts with the number part, which is in the form [0-9]+(\.[0-9]+)* (a positive integer, followed by zero or more dot-prefixed positive integers).

This may optionally be followed by one of [a-z] (a lowercase letter).

This may be followed by zero or more of the suffixes _alpha, _beta, _pre, _rc or _p, which themselves may be suffixed by an optional integer.

This may optionally be followed by the suffix -r followed immediately by an integer (the “revision number”). If this suffix is not present, it is assumed to be -r0.

3.3 Version Comparison

Version specifications are compared component by component, moving from left to right, as detailed in Algorithm 1 and sub-algorithms. If a sub-algorithm returns a decision, then that is the result of the whole comparison; if it terminates without returning a decision, the process continues from the point from which it was invoked.

3.4 Uniqueness of versions

No two packages in a given repository may have the same qualified package name and equal versions. For example, a repository may not contain more than one of foo-bar/baz-1.0.2, foo-bar/baz-1.0.2-r0 and foo-bar/baz-1.000.2.

Chapter 4
Tree Layout

This chapter defines the layout on-disk of an ebuild repository. In all cases below where a file or directory is specified, a symlink to a file or directory is also valid. In this case, the package manager must follow the operating system’s semantics for symbolic links and must not behave differently from normal.

4.1 Top Level

An ebuild repository shall occupy one directory on disk, with the following subdirectories:

• One directory per category, whose name shall be the name of the category. The layout of these directories shall be as described in section 4.2.
• A profiles directory, described in section 4.4.
• A licenses directory (optional), described in section 4.5.
• An eclass directory (optional), described in section 4.6.
• A metadata directory (optional), described in section 4.7.
• Other optional support files and directories (skeleton ebuilds or ChangeLogs, for example) may exist but are not covered by this specification. The package manager must ignore any of these files or directories that it does not recognise.

4.2 Category Directories

Each category provided by the repository (see also: the profiles/categories file, section 4.4) shall be contained in one directory, whose name shall be that of the category. Each category directory shall contain:

• A metadata.xml file, as described in appendix A. Optional.
• Zero or more package directories, one for each package in the category, as described in section 4.3. The name of the package directory shall be the corresponding package name.

Category directories may contain additional files, whose purpose is not covered by this specification. Additional directories that are not for a package may not be present, to avoid conflicts with package name directories; an exception is made for filesystem components whose name starts with a dot, which the package manager must ignore, and for any directory named CVS.

It is not required that a directory exists for each category provided by the repository. A category directory that does not exist shall be considered equivalent to an empty category (and by extension, a package manager may treat an empty category as a category that does not exist).

4.3 Package Directories

A package directory contains the following:

• Zero or more ebuilds. These are as described in section 7 and others.
• A metadata.xml file, as described in appendix A. Optional only for legacy support.
• A ChangeLog, in a format determined by the provider of the respository. Optional.
• A Manifest file, whose format is described in [1].
• A files directory, containing any support files needed by the ebuilds. Optional.

Any ebuild in a package directory must be named name-ver.suffix, where:

• name is the (unqualified) package name.
• ver is the package’s version.
• suffix is ebuild.

Package managers must ignore any ebuild file that does not match these rules.

A package directory that contains no correctly named ebuilds shall be considered a package with no versions. A package with no versions shall be considered equivalent to a package that does not exist (and by extension, a package manager may treat a package that does not exist as a package with no versions).

A package directory may contain other files or directories, whose purpose is not covered by this specification.

4.4 The Profiles Directory

The profiles directory shall contain zero or more profile directories as described in section 5, as well as the following files and directories. In any line-based file, lines beginning with a # character are treated as comments, whilst blank lines are ignored. All contents of this directory, with the exception of repo_name, are optional.

The profiles directory may contain an eapi file. This file, if it exists, must contain a single line with the name of an EAPI. This specifies the EAPI to use when handling the profiles directory; a package manager must not attempt to use any repository whose profile directory requires an EAPI it does not support. If no eapi file is present, EAPI 0 shall be used.

If the repository is not intended to be stand-alone, the contents of these files are to be taken from or merged with the master repository as necessary.

Other files not described by this specification may exist, but may not be relied upon. The package manager must ignore any files in this directory that it does not recognise.

arch.list

Contains a list, one entry per line, of permissible values for the ARCH variable, and hence permissible keywords for packages in this repository.

categories

Contains a list, one entry per line, of categories provided by this repository.

eapi

See above.

info_pkgs

Contains a list, one entry per line, of qualified package names. Any package matching one of these is to be listed when a package manager displays a ‘system information’ listing.

info_vars

Contains a list, one entry per line, of profile, configuration, and environment variables which are considered to be of interest. The value of each of these variables may be shown when the package manager displays a ‘system information’ listing.

package.mask

Contains a list, one entry per line, of package dependency specifications (using the directory’s EAPI). Any package version matching one of these is considered to be masked, and will not be installed regardless of profile unless it is unmasked by the user configuration.

profiles.desc

Described below in section 4.4.1.

repo_name

Contains, on a single line, the name of this repository. The repository name must conform to section 3.1.5.

thirdpartymirrors

Described below in section 4.4.2.

use.desc

Contains descriptions of valid global USE flags for this repository. The format is described in section 4.4.3.

use.local.desc

Contains descriptions of valid local USE flags for this repository, along with the packages to which they apply. The format is as described in section 4.4.3.

desc/

This directory contains files analogous to use.desc for the various USE_EXPAND variables. Each file in it is named <varname>.desc, where <varname> is the variable name, in lowercase, whose possible values the file describes. The format of each file is as for use.desc, described in section 4.4.3. The USE_EXPAND name is not included as a prefix here.

updates/

This directory is described in section 4.4.4.

4.4.1 The profiles.desc file

profiles.desc is a line-based file, with the standard commenting rules from section 4.4, containing a list of profiles that are valid for use, along with their associated architecture and status. Each line has the format:

Where:

• <keyword> is the default keyword for the profile and the ARCH for which the profile is valid.
• <profile path> is the (relative) path from the profiles directory to the profile in question.
• <stability> indicates the stability of the profile. This may be useful for QA tools, which may wish to display warnings with a reduced severity for some profiles. The values stable and dev are widely used, but repositories may use other values.

Fields are whitespace-delimited.

4.4.2 The thirdpartymirrors file

thirdpartymirrors is another simple line-based file, describing the valid mirrors for use with mirror:// URIs in this repository, and the associated download locations. The format of each line is:

Fields are whitespace-delimited. When parsing a URI of the form mirror://name/path/filename, where the path/ part is optional, the thirdpartymirrors file is searched for a line whose first field is name. Then the download URIs in the subsequent fields have path/filename appended to them to generate the URIs from which a download is attempted.

Each mirror name may appear at most once in a file. Behaviour when a mirror name appears multiple times is undefined. Behaviour when a mirror is defined in terms of another mirror is undefined. A package manager may choose to fetch from all of or a subset of the listed mirrors, and may use an order other than the one described.

The mirror with the name equal to the repository’s name (and if the repository has a master, the master’s name) may be consulted for all downloads.

4.4.3 use.desc and related files

use.desc contains descriptions of every valid global USE flag for this repository. It is a line-based file with the standard rules for comments and blank lines. The format of each line is:

use.local.desc contains descriptions of every valid local USE flag—those that apply only to a small number of packages, or that have different meanings for different packages. Its format is:

Flags must be listed once for each package to which they apply, or if a flag is listed in both use.desc and use.local.desc, it must be listed once for each package for which its meaning differs from that described in use.desc.

4.4.4 The updates directory

The updates directory is used to inform the package manager that a package has moved categories, names, or that a version has changed SLOT. It contains one file per quarter year, named [1-4]Q-[YYYY] for the first to fourth quarter of a given year, for example 1Q-2004 or 3Q-2006. The format of each file is again line-based, with each line having one of the following formats:

The first form, where qpn1 and qpn2 are qualified package names, instructs the package manager that the package qpn1 has changed name, category, or both, and is now called qpn2.

The second form instructs the package manager that any currently installed package version matching package dependency specification spec whose SLOT is set to slot1 should have it updated to slot2.

Any name that has appeared as the origin of a move must not be reused in the future. Any slot that has appeared as the origin of a slot move may not be used by packages matching the spec of that slot move in the future.

4.5 The Licenses Directory

The licenses directory shall contain copies of the licenses used by packages in the repository. Each file will be named according to the name used in the LICENSE variable as described in section 8.2, and will contain the complete text of the license in human-readable form. Plain text format is strongly preferred but not required.

4.6 The Eclass Directory

The eclass directory shall contain copies of the eclasses provided by this repository. The format of these files is described in section 11. It may also contain, in their own directory, support files needed by these eclasses.

4.7 The Metadata Directory

The metadata directory contains various repository-level metadata that is not contained in profiles/. All contents are optional. In this standard only the cache subdirectory is described; other contents are optional but may include security advisories, DTD files for the various XML files used in the repository, and repository timestamps.

4.7.1 The metadata cache

The metadata/cache directory may contain a cached form of all important ebuild metadata variables. The contents of this directory are described in section 14.

Chapter 5
Profiles

5.1 General principles

Generally, a profile defines information specific to a certain ‘type’ of system—it lies somewhere between repository-level defaults and user configuration in that the information it contains is not necessarily applicable to all machines, but is sufficiently general that it should not be left to the user to configure it. Some parts of the profile can be overridden by user configuration, some only by another profile.

The format of a profile is relatively simple. Each profile is a directory containing any number of the files described in this chapter, and possibly inheriting another profile. The files themselves follow a few basic conventions as regards inheritance and format; these are described in the next section. It may also contain any number of subdirectories containing other profiles.

5.2 Files that make up a profile

5.2.1 The parent file

A profile may contain a parent file. Each line must contain a relative path to another profile which will be considered as one of this profile’s parents. Any settings from the parent are inherited by this profile, and can be overridden by it. Precise rules for how settings are combined with the parent profile vary between files, and are described below. Parents are handled depth first, left to right, with duplicate parent paths being sourced for every time they are encountered.

It is illegal for a profile’s parent tree to contain cycles. Package manager behaviour upon encountering a cycle is undefined.

This file must not contain comments, blank lines or make use of line continuations.

5.2.2 The eapi file

A profile directory may contain an eapi file. This file, if it exists, must contain a single line with the name of an EAPI. This specifies the EAPI to use when handling the directory in question; a package manager must not attempt to use any profile using a directory which requires an EAPI it does not support. If no eapi file is present, EAPI 0 shall be used. The EAPI is not inherited via the parent file.

5.2.3 deprecated

If a profile contains a file named deprecated, it is treated as such. The first line of this file should contain the path from the profiles directory of the repository to a valid profile that is the recommended upgrade path from this profile. The remainder of the file can contain any text, which may be displayed to users using this profile by the package manager. This file is not inherited—profiles which inherit from a deprecated profile are not deprecated.

This file must not contain comments or make use of line continuations.

5.2.4 make.defaults

make.defaults is used to define defaults for various environment and configuration variables. This file is unusual in that it is not combined at a file level with the parent—instead, each variable is combined or overridden individually as described in section 5.3.

The file itself is a line-based key-value format. Each line contains a single VAR="value" entry, where the value must be double quoted. A variable name must start with one of a-zA-Z and may contain a-zA-Z0-9_ only. Additional syntax, which is a small subset of bash syntax, is allowed as follows:

• Variables to the right of the equals sign in the form ${foo} or $foo are recognised and expanded from variables previously set in this or earlier make.defaults files.
• One logical line may be continued over multiple physical lines by escaping the newline with a backslash. A quoted string may also continue over multiple physical lines in this fashion, so that the quoted string can begin, continue, and end on two or more separate lines.
• Backslashes, except for line continuations, are not allowed.

5.2.5 virtuals

The virtuals file defines default providers for “old-style” virtual packages. It is a simple line-based file, with each line containing two whitespace-delimited tokens. The first is a virtual package name (for example, virtual/alsa) and the second is a qualified package name. Blank lines and those beginning with a # character are ignored. When attempting to resolve a virtual name to a concrete package, the specification defined in the active profile’s virtuals list should be used if no provider is already installed.

The virtuals file is inherited in the simplest manner: all entries from the parent profile are loaded, then entries from the current profile. If a virtual package name appears in both, the entry in the parent profile is discarded.

5.2.6 Simple line-based files

These files are a simple one-item-per-line list, which is inherited in the following manner: the parent profile’s list is taken, and the current profile’s list appended. If any line begins with a hyphen, then any lines previous to it whose contents are equal to the remainder of that line are removed from the list. Once again, blank lines and those beginning with a # are discarded.

5.2.7 packages

The packages file is used to define the ‘system set’ for this profile. After the above rules for inheritance and comments are applied, its lines must take one of two forms: a package dependency specification prefixed by * denotes that the atom forms part of the system set. A package dependency specification on its own may also appear for legacy reasons, but should be ignored when calculating the system set.

5.2.8 packages.build

The packages.build file is used by Gentoo’s Catalyst tool to generate stage1 tarballs, and has no relevance to the operation of a package manager. It is thus outside the scope of this document, but is mentioned here for completeness.

5.2.9 package.mask

package.mask is used to prevent packages from being installed on a given profile. Each line contains one package dependency specification; anything matching this specification will not be installed unless unmasked by the user’s configuration.

Note that the -spec syntax can be used to remove a mask in a parent profile, but not necessarily a global mask (from profiles/package.mask, section 4.4).

Note: Portage currently treats profiles/package.mask as being on the leftmost branch of the inherit tree when it comes to -lines. This behaviour may not be relied upon.

5.2.10 package.provided

package.provided is used to tell the package manager that a certain package version should be considered to be provided by the system regardless of whether it is actually installed. Because it has severe adverse effects on USE-based and slot-based dependencies, its use is strongly deprecated and package manager support must be regarded as purely optional.

5.2.11 package.use

The package.use file may be used by the package manager to override the default USE flags specified by make.defaults on a per package basis. The format is to have a package dependency specification, and then a space delimited list of USE flags to enable. A USE flag in the form of -flag indicates that the package should have the USE flag disabled. The package dependency specification is limited to the forms defined by the directory’s EAPI.

5.2.12 USE masking and forcing

This section covers the four files use.mask, use.force, package.use.mask and package.use.force. They are described together because they interact in a non-trivial manner.

Simply speaking, use.mask and use.force are used to say that a given USE flag must never or always, respectively, be enabled when using this profile. package.use.mask and package.use.force do the same thing on a per-package, or per-version, basis. The precise manner in which they interact is less simple, and is best described in terms of the algorithm used to determine whether a flag is masked for a given package version. This is described in Algorithm 8.

The logic for use.force and package.use.force is identical. If a flag is both masked and forced, the mask is considered to take precedence.

USE_EXPAND values may be forced or masked by using expand_name_value.

A package manager may treat ARCH values that are not the current architecture as being masked.

5.3 Profile variables

This section documents variables that have special meaning, or special behaviour, when defined in a profile’s make.defaults file.

5.3.1 Incremental Variables

Incremental variables must stack between parent and child profiles in the following manner: Beginning with the highest parent profile, tokenise the variable’s value based on whitespace and concatenate the lists. Then, for any token T beginning with a hyphen, remove it and any previous tokens whose value is equal to T with the hyphen removed, or, if T is equal to -*, remove all previous values. Note that because of this treatment, the order of tokens in the final result is arbitrary, not necessarily related to the order of tokens in any given profile. The following variables must be treated in this fashion:

• USE
• USE_EXPAND
• USE_EXPAND_HIDDEN
• CONFIG_PROTECT
• CONFIG_PROTECT_MASK

If the package manager supports any EAPI listed in table 5.1 as using profile-defined IUSE injection, the following variables must also be treated incrementally; otherwise, the following variables may or may not be treated incrementally:

• IUSE_IMPLICIT
• USE_EXPAND_IMPLICIT
• USE_EXPAND_UNPREFIXED

Other variables, except where they affect only package-manager-specific functionality (such as Portage’s FEATURES variable), must not be treated incrementally—later definitions shall completely override those in parent profiles.

5.3.2 Specific variables and their meanings

The following variables have specific meanings when set in profiles.

ARCH

The system’s architecture. Must be a value listed in profiles/arch.list; see section 4.4 for more information. Must be equal to the primary KEYWORD for this profile.

CONFIG_PROTECT, CONFIG_PROTECT_MASK

Contain whitespace-delimited lists used to control the configuration file protection. Described more fully in chapter 13.3.3.

USE

Defines the list of default USE flags for this profile. Flags may be added or removed by the user’s configuration. USE_EXPAND values must not be specified in this way.

USE_EXPAND

Defines a list of variables which are to be treated incrementally and whose contents are to be expanded into the USE variable as passed to ebuilds. See section 12.1.1 for details.

USE_EXPAND_UNPREFIXED

Similar to USE_EXPAND, but no prefix is used. If the repository contains any package using an EAPI supporting profile-defined IUSE injection (see table 5.1), this list must contain at least ARCH. See section 12.1.1 for details.

USE_EXPAND_HIDDEN

Contains a (possibly empty) subset of names from USE_EXPAND and USE_EXPAND_UNPREFIXED. The package manager may use this set as a hint to avoid displaying uninteresting or unhelpful information to an end user.

USE_EXPAND_IMPLICIT, IUSE_IMPLICIT

Used to inject implicit values into IUSE. See section 12.1.1 for details.

In addition, for EAPIs listed in table 5.1 as supporting profile defined IUSE injection, the variables named in USE_EXPAND and USE_EXPAND_UNPREFIXED have special handling as described in section 12.1.1.

Any other variables set in make.defaults must be passed on into the ebuild environment as-is, and are not required to be interpreted by the package manager.

Chapter 6
Old-Style Virtual Packages

Old-style virtuals are pseudo-packages—they can be depended upon or installed, but do not exist in the ebuild repository. An old-style virtual requires several things in the repository: at least one ebuild must list the virtual in its PROVIDE variable, and there must be at least one entry in a profiles virtuals file listing the default provider for each profile—see sections 8.3 and 5.2.5 for specifics on these two. Old-style virtuals require special handling as regards dependencies; this is described below.

All old-style virtuals must use the category virtual. Not all packages using the virtual category may be assumed to be old style virtuals.

Note: A new-style virtual is simply an ebuild which install no files and use its dependency strings to select providers. By convention, and to ease migration, these are also placed in the virtual category.

6.1 Dependencies on virtual packages

When a dependency on a virtual package is encountered, it must be resolved into a real package before it can be satisfied. There are two factors that affect this process: whether a package providing the virtual is installed, and the virtuals file in the active profile (section 5.2.5). If a package is already installed which satisfies the virtual requirement (via PROVIDE), then it should be used to satisfy the dependency. Otherwise, the profiles virtuals file (section 5.2.5) should be consulted to choose an appropriate provider.

Dependencies on old style virtuals must not use any kind of version restriction.

Blocks on provided virtuals have special behaviour documented in section 9.2.4.

Chapter 7
Ebuild File Format

The ebuild file format is in its basic form a subset of the format of a bash script. The interpreter is assumed to be GNU bash, version 3.2 or later, see footnote 6 on page 172. The file encoding must be UTF-8 with Unix-style newlines. When sourced, the ebuild must define certain variables and functions (see sections 8 and 10 for specific information), and must not call any external programs, write anything to standard output or standard error, or modify the state of the system in any way.

Chapter 8
Ebuild-defined Variables

Note: This section describes variables that may or must be defined by ebuilds. For variables that are passed from the package manager to the ebuild, see section 12.1.

8.1 Metadata invariance

All ebuild-defined variables discussed in this chapter must be defined independently of any system, profile or tree dependent data, and must not vary depending upon the ebuild phase. In particular, ebuild metadata can and will be generated on a different system from that upon which the ebuild will be used, and the ebuild must generate identical metadata every time it is used.

Globally defined ebuild variables without a special meaning must similarly not rely upon variable data.

8.2 Mandatory Ebuild-defined Variables

All ebuilds must define at least the following variables:

DESCRIPTION

A short human-readable description of the package’s purpose. May be defined by an eclass. Must not be empty.

HOMEPAGE

The URI or URIs for a package’s homepage, including protocols. May be defined by an eclass. See section 9 for full syntax.

IUSE

The USE flags used by the ebuild. Any eclass that works with USE flags must also set IUSE, listing only the variables used by that eclass. The package manager is responsible for merging these values. See section 12.1.1 for discussion on which values must be listed this variable.

IUSE-DEFAULTS

In EAPIs shown in table 8.1 as supporting IUSE defaults, any use flag name in IUSE may be prefixed by at most one of a plus or a minus sign. If such a prefix is present, the package manager may use it as a suggestion as to the default value of the use flag if no other configuration overrides it.

KEYWORDS

A whitespace separated list of keywords for the ebuild. Each token must be a valid keyword name, as per section 3.1.6. May include -*, which indicates that the package will only work on explicitly listed archs. May include -arch, which indicates that the package will not work on the specified arch. May be empty, which indicates uncertain functionality on any architecture. May be defined in an eclass.

LICENSE

The package’s license. Each text token must correspond to a tree “licenses/” entry (see section 4.5). See section 9 for full syntax. May be defined by an eclass.

SLOT

The package’s slot. Must be a valid slot name, as per section 3.1.3. May be defined by an eclass. Must not be empty.

SRC_URI

A list of source URIs for the package. Valid protocols are http://, https://, ftp:// and mirror:// (see section 4.4.2 for mirror behaviour). Fetch restricted packages may include URL parts consisting of just a filename. See section 9 for full syntax.

If any of these variables are undefined, or if any of these variables are set to invalid values, the package manager’s behaviour is undefined; ideally, an error in one ebuild should not prevent operations upon other ebuilds or packages.

8.3 Optional Ebuild-defined Variables

Ebuilds may define any of the following variables:

DEPEND

See section 9.

EAPI

The EAPI. See below for defaults.

PDEPEND

See section 9.

PROVIDE

Zero or more qualified package names of any old style virtuals provided by this package. See section 9 for full syntax.

RDEPEND

See section 9. For some EAPIs, RDEPEND has special behaviour for its value if unset and when used with an eclass. See section 8.3.2 for details.

RESTRICT

Zero or more behaviour restrictions for this package. See section 9.2.5 for value meanings and section 9 for full syntax.

PROPERTIES

PROPERTIES Zero or more properties for this package. See section 9.2.6 for value meanings and section 9 for full syntax. For EAPIs listed in table 8.2 as having optional support, ebuilds must not rely upon the package manager recognising or understanding this variable in any way.

S

The path to the temporary build directory, used by src_compile, src_install etc. Defaults to ${WORKDIR}/${P}.

8.3.1 EAPI

An empty or unset EAPI value is equivalent to 0. Ebuilds must not assume that they will get a particular one of these two values if they are expecting one of these two values.

The package manager must either pre-set the EAPI variable to 0 or ensure that it is unset before sourcing the ebuild for metadata generation. When using the ebuild for other purposes, the package manager must either pre-set EAPI to the value specified by the ebuild’s metadata or ensure that it is unset.

If any of these variables are set to invalid values, the package manager’s behaviour is undefined; ideally, an error in one ebuild should not prevent operations upon other ebuilds or packages.

8.3.2 RDEPEND value

RDEPEND-DEPEND

In EAPIs listed in table 8.3 as having RDEPEND=DEPEND, if RDEPEND is unset (but not if it is set to an empty string) in an ebuild, the package manager must set its value to be equal to the value of DEPEND.

When dealing with eclasses, only values set in the ebuild itself are considered for this behaviour; any DEPEND or RDEPEND set in an eclass does not change the implicit RDEPEND=DEPEND for the ebuild portion, and any DEPEND value set in an eclass does not get added to RDEPEND.

8.4 Magic Ebuild-defined Variables

The following variables must be defined by inherit (see section 11.1, and may be considered to be part of the ebuild’s metadata:

ECLASS

The current eclass, or unset if there is no current eclass. This is handled magically by inherit and must not be modified manually.

INHERITED

List of inherited eclass names. Again, this is handled magically by inherit.

Note: Thus, by extension of section 8.1, inherit may not be used conditionally, except upon constant conditions.

The following are special variables defined by the package manager for internal use and may or may not be exported to the ebuild environment:

DEFINED_PHASES

DEFINED-PHASES A space separated arbitrarily ordered list of phase names (e.g. configure setup unpack) whose phase functions are defined by the ebuild or an eclass inherited by the ebuild. If no phase functions are defined, a single hyphen is used instead of an empty string. For EAPIs listed in table 8.4 as having optional DEFINED_PHASES support, package managers may not rely upon the metadata cache having this variable defined, and must treat an empty string as “this information is not available”.

Note: Thus, by extension of section 8.1, phase functions must not be defined based upon any variant condition.

Chapter 9
Dependencies

9.1 Dependency Classes

There are three classes of dependencies supported by ebuilds:

• Build dependencies (DEPEND). These must be installed and usable before the ebuild is installed.
• Runtime dependencies (RDEPEND). These must be installed and usable before the ebuild is treated as usable.
• Post dependencies (PDEPEND). These must be installed at some point.

In addition, SRC_URI, HOMEPAGE, PROVIDE, RESTRICT, PROPERTIES and LICENSE use dependency-style specifications to specify their values.

9.2 Dependency Specification Format

The following elements are recognised in at least one class of specification. All elements must be surrounded on both sides by whitespace, except at the start and end of the string.

• A package dependency specification. Permitted in DEPEND, RDEPEND, PDEPEND.
• A simple qualified package name. Permitted in PROVIDE (and inside DEPEND etc via the previous item).
• A URI, in the form proto://host/path. Permitted in SRC_URI and HOMEPAGE. In EAPIs listed in table 9.1 as supporting SRC_URI arrows, may optionally be followed by whitespace, then ->, then whitespace, then a simple filename when in SRC_URI. For SRC_URI behaviour, see section 9.2.7.
• A flat filename. Permitted in SRC_URI.
• A license name (e.g. GPL-2). Permitted in LICENSE.
• A simple string. Permitted in RESTRICT and PROPERTIES.
• An all-of group, which consists of an open parenthesis, followed by whitespace, followed by zero or more of (a dependency item of any kind followed by whitespace), followed by a close parenthesis. More formally: all-of ::= ’(’ whitespace (item whitespace)* ’)’. Permitted in all specification style variables.
• An any-of group, which consists of the string ||, followed by whitespace, followed by an open parenthesis, followed by whitespace, followed by zero or more of (a dependency item of any kind followed by whitespace), followed by a close parenthesis. More formally: any-of ::= ’||’ whitespace ’(’ whitespace (item whitespace)* ’)’. Permitted in DEPEND, RDEPEND, PDEPEND, LICENSE.
• A use-conditional group, which consists of an optional exclamation mark, followed by a use flag name, followed by a question mark, followed by whitespace, followed by an open parenthesis, followed by whitespace, followed by zero or more of (a dependency item of any kind followed by whitespace), followed by a close parenthesis. More formally: use-conditional ::= ’!’? flag-name ’?’ whitespace ’(’ whitespace (item whitespace)* ’)’. Permitted in all specification style variables.

In particular, note that whitespace is not optional.

9.2.1 All-of Dependency Specifications

In an all-of group, all of the child elements must be matched.

9.2.2 Use-conditional Dependency Specifications

In a use-conditional group, if the associated use flag is enabled (or disabled if it has an exclamation mark prefix), all of the child elements must be matched.

It is an error for a flag to be used if it is not included in IUSE_EFFECTIVE as described in section 12.1.1.

9.2.3 Any-of Dependency Specifications

Any use-conditional group that is an immediate child of an any-of group, if not enabled (disabled for an exclamation mark prefixed use flag name), is not considered a member of the any-of group for match purposes.

In an any-of group, at least one immediate child element must be matched. A blocker is considered to be matched if its associated package dependency specification is not matched.

An empty any-of group counts as being matched.

9.2.4 Package Dependency Specifications

A package dependency can be in one of the following base formats. A package manager must warn or error on non-compliant input.

• A simple category/package name.
• An operator, as described in section 9.2.4, followed immediately by category/package, followed by a hyphen, followed by a version specification.

In EAPIs shown in table 9.2 as supporting SLOT dependencies, either of the above formats may additionally be suffixed by a :slot restriction, as described in section 9.2.4. A package manager must warn or error if slot dependencies are used with an EAPI not supporting SLOT dependencies.

USE-DEPS

In EAPIs shown in table 9.3 as supporting 2-style or 4-style USE dependencies, a specification may additionally be suffixed by at most one 2-style or 4-style [use] restriction, as described in section 9.2.4. A package manager must warn or error if this feature is used with an EAPI not supporting use dependencies.

Note: Order is important. The slot restriction must come before use dependencies.

Operators

The following operators are available:

<

Strictly less than the specified version.

<=

Less than or equal to the specified version.

=

Exactly equal to the specified version. Special exception: if the version specified has an asterisk immediately following it, a string prefix comparison is used instead. When an asterisk is used, the specification must remain valid if the asterisk were removed. (An asterisk used with any other operator is illegal.)

~

Equal to the specified version, except the revision part of the matching package may be greater than the revision part of the specified version (-r0 is assumed if no revision is explicitly stated).

>=

Greater than or equal to the specified version.

>

Strictly greater than the specified version.

Block Operator

If the specification is prefixed with one or two exclamation marks, the named dependency is a block rather than a requirement—that is to say, the specified package must not be installed, with the following exceptions:

• Blocks on a package provided exclusively by the ebuild do not count.
• Blocks on the ebuild itself do not count.

BANG-STRENGTH

There are two strengths of block: weak and strong. A weak block may be ignored by the package manager, so long as any blocked package will be uninstalled later on. A strong block must not be ignored. The mapping from one or two exclamation marks to strength is described in table 9.4.

Slot Dependencies

SLOT-DEPS

A named slot dependency consists of a colon followed by a slot name. A specification with a named slot dependency matches only if the slot of the matched package is equal to the slot specified. If the slot of the package to match cannot be determined (e.g. because it is not a supported EAPI), the match is treated as unsuccessful.

SLOT-OPERATOR-DEPS

An operator slot dependency consists of a colon followed by one of the following operators:

*

Indicates that any slot value is acceptable. In addition, for runtime dependencies, indicates that the package will not break if the matched package is uninstalled and replaced by a different matching package in a different slot.

=

Indicates that any slot value is acceptable. In addition, for runtime dependencies, indicates that the package will break unless a matching package with slot equal to the slot of the best installed version at the time the package was installed is available.

To implement the equals slot operator, the package manager will need to store the slot of the best installed version of the matching package. The package manager may do this by appending the appropriate slot after the equals sign when saving the package’s dependencies. This syntax is only for package manager use and must not be used by ebuilds.

2-Style and 4-Style Use Dependencies

A 2-style or 4-style use dependency consists of one of the following:

[opt]

The flag must be enabled.

[opt=]

The flag must be enabled if the flag is enabled for the package with the dependency, or disabled otherwise.

[!opt=]

The flag must be disabled if the flag is enabled for the package with the dependency, or enabled otherwise.

[opt?]

The flag must be enabled if the flag is enabled for the package with the dependency.

[!opt?]

The flag must be disabled if the use flag is disabled for the package with the dependency.

[-opt]

The flag must be disabled.

Multiple requirements may be combined using commas, e.g. [first,-second,third?].

When multiple requirements are specified, all must match for a successful match.

USE-DEP-DEFAULTS

In a 4-style use dependency, the flag name may immediately be followed by a default specified by either (+) or (-). The former indicates that, when applying the use dependency to a package that does not have the flag in question in IUSE_REFERENCEABLE, the package manager shall behave as if the flag were present and enabled; the latter, present and disabled.

Unless a 4-style default is specified, it is an error for a use dependency to be applied to an ebuild which does not have the flag in question in IUSE_REFERENCEABLE.

Note: By extension of the above, a default that could reference an ebuild using an EAPI not supporting profile IUSE injections cannot rely upon any particular behaviour for flags that would not have to be part of IUSE.

It is an error for an ebuild to use a conditional use dependency when that ebuild does not have the flag in IUSE_EFFECTIVE.

9.2.5 Restrict

The following tokens are permitted inside RESTRICT:

mirror

The package’s SRC_URI entries may not be mirrored, and mirrors should not be checked when fetching.

fetch

The package’s SRC_URI entries may not be downloaded automatically. If entries are not available, pkg_nofetch is called.

strip

No stripping of debug symbols from files to be installed may be performed.

userpriv

The package manager may not drop root privileges when building the package.

test

The src_test phase must not be run.

sandbox

The sandbox tool must not be used when building the package.

Package managers may recognise other tokens, but ebuilds may not rely upon them being supported.

9.2.6 Properties

The following tokens are permitted inside PROPERTIES:

interactive

The package may require interaction with the user via the tty.

Ebuilds may not rely upon any token being supported.

9.2.7 SRC_URI

All filename components that are enabled (i.e. not inside a use-conditional block that is not matched) in SRC_URI must be available in the DISTDIR directory. In addition, these components are used to make the A and AA variables.

If a component contains a full URI with protocol, that download location must be used. Package managers may also consult mirrors for their files.

The special mirror:// protocol must be supported. See section 4.4.2 for mirror details.

If a simple filename rather than a full URI is provided, the package manager can only use mirrors to download the file.

The RESTRICT metadata key can be used to impose additional restrictions upon downloading—see section 9.2.5 for details.

SRC-URI-ARROWS

In EAPIs supporting arrows, if an arrow is used, the filename used when saving to DISTDIR shall instead be the name on the right of the arrow. When consulting mirrors (except for those explicitly listed on the left of the arrow, if mirror:// is used), the filename to the right of the arrow shall be requested instead of the filename in the URI.

Chapter 10
Ebuild-defined Functions

10.1 List of Functions

The following is a list of functions that an ebuild, or eclass, may define, and which will be called by the package manager as part of the build and/or install process. In all cases the package manager must provide a default implementation of these functions; unless otherwise stated this must be a no-op. Most functions must assume only that they have write access to the package’s working directory (the WORKDIR environment variable; see section 12.1), and the temporary directory T; exceptions are noted below. All functions may assume that they have read access to all system libraries, binaries and configuration files that are accessible to normal users.

The environment for functions run outside of the build sequence (that is, pkg_config, pkg_info, pkg_prerm and pkg_postrm) must be the environment used for the build of the package, not the current configuration.

Ebuilds must not call nor assume the existence of any phase functions.

10.1.1 Initial Working Directories

Some functions may assume that their initial working directory is set to a particular location; these are noted below. If no initial working directory is mandated, it may be set to anything and the ebuild must not rely upon a particular location for it. The ebuild may assume that the initial working directory for any phase is a trusted location that may only be written to by a privileged user and group.

S-WORKDIR-FALLBACK

Some functions are described as having an initial working directory of S with an error or fallback to WORKDIR. For EAPIs listed in table 10.1 as having the fallback, this means that if S is not a directory before the start of the phase function, the initial working directory shall be WORKDIR instead. For EAPIs where it is a conditional error, if S is not a directory before the start of the phase function, it is a fatal error, unless all of the following conditions are true, in which case the fallback to WORKDIR is used:

• The A variable contains no items.
• The phase function in question is not in DEFINED_PHASES.
• None of the phase functions unpack, prepare, configure, compile or install, if supported by the EAPI in question and occurring prior to the phase about to be executed, are in DEFINED_PHASES.

10.1.2 pkg_pretend

PKG-PRETEND

The pkg_pretend function is only called for EAPIs listed in table 10.2 as supporting it.

The pkg_pretend function may be used to carry out sanity checks early on in the install process. For example, if an ebuild requires a particular kernel configuration, it may perform that check in pkg_pretend and call eerror and then die with appropriate messages if the requirement is not met.

pkg_pretend is run separately from the main phase function sequence, and does not participate in any kind of environment saving. There is no guarantee that any of an ebuild’s dependencies will be met at this stage, and no guarantee that the system state will not have changed substantially before the next phase is executed.

pkg_pretend must not write to the filesystem.

10.1.3 pkg_setup

The pkg_setup function sets up the ebuild’s environment for all following functions, before the build process starts. Further, it checks whether any necessary prerequisites not covered by the package manager, e.g. that certain kernel configuration options are fulfilled.

pkg_setup must be run with full filesystem permissions, including the ability to add new users and/or groups to the system.

10.1.4 src_unpack

SRC-UNPACK

The src_unpack function extracts all of the package’s sources. In EAPIs lacking src_prepare, it may also apply patches and set up the package’s build system for further use.

The initial working directory must be WORKDIR, and the default implementation used when the ebuild lacks the src_unpack function shall behave as:

10.1.5 src_prepare

SRC-PREPARE

The src_prepare function is only called for EAPIs listed in table 10.3 as supporting it.

The src_prepare function can be used for post-unpack source preparation. The default implementation does nothing.

The initial working directory is S, with an error or fallback to WORKDIR as discussed in section 10.1.1.

10.1.6 src_configure

SRC-CONFIGURE

The src_configure function is only called for EAPIs listed in table 10.4 as supporting it.

The initial working directory is S, with an error or fallback to WORKDIR as discussed in section 10.1.1.

The src_configure function configures the package’s build environment. The default implementation used when the ebuild lacks the src_configure function shall behave as:

10.1.7 src_compile

SRC-COMPILE

The src_compile function configures the package’s build environment in EAPIs lacking src_configure, and builds the package in all EAPIs.

The initial working directory is S, with an error or fallback to WORKDIR as discussed in section 10.1.1.

SRC-COMPILE-0

For EAPIs listed in table 10.5 as using format 0, the default implementation used when the ebuild lacks the src_compile function shall behave as:

SRC-COMPILE-1

For EAPIs listed in table 10.5 as using format 1, the default implementation used when the ebuild lacks the src_compile function shall behave as:

SRC-COMPILE-2

For EAPIs listed in table 10.5 as using format 2, the default implementation used when the ebuild lacks the src_compile function shall behave as:

10.1.8 src_test

The src_test function runs unit tests for the newly built but not yet installed package as provided.

The initial working directory must be S if that exists, falling back to WORKDIR otherwise. The default implementation used when the ebuild lacks the src_test function must, if tests are enabled, run make check if and only if such a target is available, or if not run make test, if and only such a target is available. In both cases, if make returns non-zero the build must be aborted.

The src_test function may be disabled by RESTRICT. See section 9.2.5.

10.1.9 src_install

SRC-INSTALL

The src_install function installs the package’s content to a directory specified in D.

The initial working directory is S, with an error or fallback to WORKDIR as discussed in section 10.1.1.

SRC-INSTALL-4

For EAPIs listed in table 10.6 as using format 4, the default implementation used when the ebuild lacks the src_install function shall behave as:

For other EAPIs, the default implementation used when the ebuild lacks the src_install function is a no-op.

10.1.10 pkg_preinst

The pkg_preinst function performs any special tasks that are required immediately before merging the package to the live filesystem. It must not write outside of the directories specified by the ROOT and D environment variables.

pkg_preinst must be run with full access to all files and directories below that specified by the ROOT and D environment variables.

10.1.11 pkg_postinst

The pkg_postinst function performs any special tasks that are required immediately after merging the package to the live filesystem. It must not write outside of the directory specified in the ROOT environment variable.

pkg_postinst, like, pkg_preinst, must be run with full access to all files and directories below that specified by the ROOT environment variable.

10.1.12 pkg_prerm

The pkg_prerm function performs any special tasks that are required immediately before unmerging the package from the live filesystem. It must not write outside of the directory specified by the ROOT environment variable.

pkg_prerm must be run with full access to all files and directories below that specified by the ROOT environment variable.

10.1.13 pkg_postrm

The pkg_postrm function performs any special tasks that are required immediately after unmerging the package from the live filesystem. It must not write outside of the directory specified by the ROOT environment variable.

pkg_postrm must be run with full access to all files and directories below that specified by the ROOT environment variable.

10.1.14 pkg_config

The pkg_config function performs any custom steps required to configure a package after it has been fully installed. It is the only ebuild function which may be interactive and prompt for user input.

pkg_config must be run with full access to all files and directories inside of ROOT.

10.1.15 pkg_info

PKG-INFO

The pkg_info function may be called by the package manager when displaying information about an installed package. In EAPIs listed in table 10.7 as supporting pkg_info on non-installed packages, it may also be called by the package manager when displaying information about a non-installed package. In this case, ebuild authors should note that dependencies may not be installed.

pkg_info must not write to the filesystem.

10.1.16 pkg_nofetch

The pkg_nofetch function is run when the fetch phase of an fetch-restricted ebuild is run, and the relevant source files are not available. It should direct the user to download all relevant source files from their respective locations, with notes concerning licensing if applicable.

pkg_nofetch must require no write access to any part of the filesystem.

10.1.17 default_ Phase Functions

DEFAULT-PHASE-FUNCS

In EAPIs listed in table 10.8 as supporting default_ phase functions, a function named default_(phase) that behaves as the default implementation for that EAPI shall be defined when executing any ebuild phase listed in the table. Ebuilds must not call these functions except when in the phase in question.

10.2 Call Order

The call order for installing a package is:

• pkg_pretend (only for EAPIs listed in table 10.2), which is called outside of the normal call order process.
• pkg_setup
• src_unpack
• src_prepare (only for EAPIs listed in table 10.3)
• src_configure (only for EAPIs listed in table 10.4)
• src_compile
• src_test (except if RESTRICT=test)
• src_install
• pkg_preinst
• pkg_postinst

The call order for uninstalling a package is:

• pkg_prerm
• pkg_postrm

The call order for reinstalling a package is:

• pkg_pretend (only for EAPIs listed in table 10.2), which is called outside of the normal call order process.
• pkg_setup
• src_unpack
• src_prepare (only for EAPIs listed in table 10.3)
• src_configure (only for EAPIs listed in table 10.4)
• src_compile
• src_test (except if RESTRICT=test)
• src_install
• pkg_preinst
• pkg_prerm for the package being replaced
• pkg_postrm for the package being replaced
• pkg_postinst

The call order for upgrading or downgrading a package is:

• pkg_pretend (only for EAPIs listed in table 10.2), which is called outside of the normal call order process.
• pkg_setup
• src_unpack
• src_prepare (only for EAPIs listed in table 10.3)
• src_configure (only for EAPIs listed in table 10.4)
• src_compile
• src_test (except if RESTRICT=test)
• src_install
• pkg_preinst
• pkg_postinst
• pkg_prerm for the package being replaced
• pkg_postrm for the package being replaced

The pkg_config, pkg_info and pkg_nofetch functions are not called in a normal sequence. The pkg_pretend function is called some unspecified time before a (possibly hypothetical) normal sequence.

For installing binary packages, the src phases are not called.

When building binary packages that are not to be installed locally, the pkg_preinst and pkg_postinst functions are not called.

Chapter 11
Eclasses

Eclasses serve to store common code that is used by more than one ebuild, which greatly aids maintainability and reduces the tree size. However, due to metadata cache issues, care must be taken in their use. In format they are similar to an ebuild, and indeed are sourced as part of any ebuild using them. The interpreter is therefore the same, and the same requirements for being parseable hold.

Eclasses must be located in the eclass directory in the top level of the repository—see section 4.6. Each eclass is a single file named <name>.eclass, where <name> is the name of this eclass, used by inherit and EXPORT_FUNCTIONS among other places.

11.1 The inherit command

An ebuild wishing to make use of an eclass does so by using the inherit command in global scope. This will cause the eclass to be sourced as part of the ebuild—any function or variable definitions in the eclass will appear as part of the ebuild, with exceptions for certain metadata variables, as described below.

The inherit command takes one or more parameters, which must be the names of eclasses (excluding the .eclass suffix and the path). For each parameter, in order, the named eclass is sourced.

Eclasses may end up being sourced multiple times.

The inherit command must also ensure that:

• The ECLASS variable is set to the name of the current eclass, when sourcing that eclass.
• Once all inheriting has been done, the INHERITED metadata variable contains the name of every eclass used, separated by whitespace.

11.2 Eclass-defined Metadata Keys

The IUSE, DEPEND, RDEPEND and PDEPEND variables are handled specially when set by an eclass. They must be accumulated across eclasses, appending the value set by each eclass to the resulting value after the previous one is loaded. Then the eclass-defined value is appended to that defined by the ebuild. In the case of RDEPEND, this is done after the implicit RDEPEND rules in section 8.3.2 are applied.

11.3 EXPORT_FUNCTIONS

There is one command available in the eclass environment that is neither available nor meaningful in ebuilds—EXPORT_FUNCTIONS. This can be used to alias ebuild phase functions from the eclass so that an ebuild inherits a default definition whilst retaining the ability to override and call the eclass-defined version from it. The use of it is best illustrated by an example; this is given in listing 11.1 and is a snippet from a hypothetical foo.eclass.

This example defines an eclass src_compile function and uses EXPORT_FUNCTIONS to alias it. Then any ebuild that inherits foo.eclass will have a default src_compile defined, but should the author wish to override it he can access the function in foo.eclass by calling foo_src_compile.

EXPORT_FUNCTIONS must only be used on ebuild phase functions. The function that is aliased must be named eclassname_phasefunctionname, where eclassname is the name of the eclass.

EXPORT_FUNCTIONS must be used at most once per eclass.

Chapter 12
The Ebuild Environment

12.1 Defined Variables

The package manager must define the following environment variables. Not all variables are meaningful in all phases; variables that are not meaningful in a given phase may be unset or set to any value. Ebuilds must not attempt to modify any of these variables, unless otherwise specified.

Because of their special meanings, these variables may not be preserved consistently across all phases as would normally happen due to environment saving (see 12.2). For example, EBUILD_PHASE is different for every phase, and ROOT may have changed between the various different pkg_* phases. Ebuilds must recalculate any variable they derive from an inconsistent variable.

Except where otherwise noted, all variables set in the active profiles’ make.defaults files must be exported to the ebuild environment. CHOST, CBUILD and CTARGET, if not set by profiles, must contain either an appropriate machine tuple (the definition of appropriate is beyond the scope of this specification) or be unset.

PATH must be initialized by the package manager to a “usable” default. The exact value here is left up to interpretation, but it should include the equivalent “sbin” and “bin” and any package manager specific directories.

GZIP, BZIP, BZIP2, CDPATH, GREP_OPTIONS, GREP_COLOR and GLOBIGNORE must not be set.

12.1.1 USE and IUSE Handling

This section discusses the handling of four variables:

IUSE

is the variable calculated from the IUSE values defined in ebuilds and eclasses.

IUSE_REFERENCEABLE

is a variable calculated from IUSE and a variety of other sources described below. It is purely a conceptual variable; it is not exported to the ebuild environment. Values in IUSE_REFERENCEABLE may legally be used in queries from other packages about an ebuild’s state (for example, for use dependencies).

IUSE_EFFECTIVE

is another conceptual, unexported variable. Values in IUSE_EFFECTIVE are those which an ebuild may legally use in queries about itself (for example, for the use function, and for use in dependency specification conditional blocks).

USE

is a variable calculated by the package manager and exported to the ebuild environment.

In all cases, the values of IUSE_REFERENCEABLE and IUSE_EFFECTIVE are undefined during metadata generation.

For EAPIs listed in table 5.1 as not supporting profile defined IUSE injection, IUSE_REFERENCEABLE is equal to the calculated IUSE value. For EAPIs where profile defined IUSE injection is supported, IUSE_REFERENCEABLE is equal to IUSE_EFFECTIVE.

For EAPIs listed in table 5.1 as not supporting profile defined IUSE injection, IUSE_EFFECTIVE contains the following values:

• All values in the calculated IUSE value.
• All possible values for the ARCH variable.
• All legal use flag names whose name starts with the lowercase equivalent of any value in the profile USE_EXPAND variable followed by an underscore.

PROFILE-IUSE-INJECTION

For EAPIs listed in table 5.1 as supporting profile defined IUSE injection, IUSE_EFFECTIVE contains the following values:

• All values in the calculated IUSE value.
• All values in the profile IUSE_IMPLICIT variable.
• All values in the profile variable named USE_EXPAND_VALUES_${v}, where ${v} is any value in the intersection of the profile USE_EXPAND_UNPREFIXED and USE_EXPAND_IMPLICIT variables.
• All values for ${lower_v}_${x}, where ${x} is all values in the profile variable named USE_EXPAND_VALUES_${v}, where ${v} is any value in the intersection of the profile USE_EXPAND and USE_EXPAND_IMPLICIT variables and ${lower_v} is the lowercase equivalent of ${v}.

The USE variable is set by the package manager. For each value in IUSE_EFFECTIVE, USE shall contain that value if the flag is to be enabled for the ebuild in question, and shall not contain that value if it is to be disabled. In EAPIs listed in table 5.1 as not supporting profile defined IUSE injection, USE may contain other flag names that are not relevant for the ebuild.

For EAPIs listed in table 5.1 as supporting profile defined IUSE injection, the variables named in USE_EXPAND and USE_EXPAND_UNPREFIXED shall have their profile-provided values reduced to contain only those values that are present in IUSE_EFFECTIVE.

For EAPIs listed in table 5.1 as supporting profile defined IUSE injection, the package manager must save the calculated value of IUSE_EFFECTIVE when installing a package. Details are beyond the scope of this specification.

12.1.2 REPLACING_VERSIONS and REPLACED_BY_VERSION

REPLACE-VERSION-VARS

In EAPIs listed in table 12.2 as supporting it, the REPLACING_VERSIONS variable shall be defined in pkg_preinst and pkg_postinst. In addition, it may be defined in pkg_pretend and pkg_setup, although ebuild authors should take care to handle binary package creation and installation correctly when using it in these phases.

REPLACING_VERSIONS is a list, not a single optional value, to handle pathological cases such as installing foo-2:2 to replace foo-2:1 and foo-3:2.

In EAPIs listed in table 12.2 as supporting it, the REPLACED_BY variable shall be defined in pkg_prerm and pkg_postrm. It shall contain at most one value.

12.1.3 Offset-prefix variables EPREFIX, EROOT and ED

OFFSET-PREFIX-VARS

Table 12.4 lists the EAPIs which support offset-prefix installations. This support was initially added in EAPI 3, in the form of three extra variables. Two of these, EROOT and ED, are convenience variables using the variable EPREFIX. In EAPIs that do not support an offset-prefix, the installation offset is hardwired to /usr. In offset-prefix supporting EAPIs the installation offset is set as ${EPREFIX}/usr and hence can be adjusted using the variable EPREFIX. Note that the behaviour of offset-prefix aware and agnostic is the same when EPREFIX is set to the empty string in offset-prefix aware EAPIs. The latter do have the variables ED and EROOT properly set, though.

12.2 The state of variables between functions

Exported and default scope variables are saved between functions. A non-local variable set in a function earlier in the call sequence must have its value preserved for later functions, including functions executed as part of a later uninstall.

Note: pkg_pretend is not part of the normal call sequence, and does not take part in environment saving.

Variables that were exported must remain exported in later functions; variables with default visibility may retain default visibility or be exported.

Variables with special meanings to the package manager are excluded from this rule.

Global variables must only contain invariant values (see 8.1). If a global variable’s value is invariant, it may have the value that would be generated at any given point in the build sequence.

This is demonstrated by code listing 12.1.

12.3 Available commands

This section documents the commands available to an ebuild. Unless otherwise specified, they may be aliases, shell functions, or executables in the ebuild’s PATH.

When an ebuild is being sourced for metadata querying rather than for a build (that is to say, when none of the src_ or pkg_ functions are to be called), no external command may be executed. The package manager may take steps to enforce this.

12.3.1 System commands

Any ebuild not listed in the system set for the active profile(s) may assume the presence of every command that is always provided by the system set for that profile. However, it must target the lowest common denominator of all systems on which it might be installed—in most cases this means that the only packages that can be assumed to be present are those listed in the base profile or equivalent, which is inherited by all available profiles. If an ebuild requires any applications not provided by the system profile, or that are provided conditionally based on USE flags, appropriate dependencies must be used to ensure their presence.

Guaranteed system commands

The following commands must always be available in the ebuild environment:

• All builtin commands in GNU bash, version 3.2⁶ .
• sed must be available, and must support all forms of invocations valid for GNU sed version 4 or later.
• patch must be available, and must support all inputs valid for GNU patch.

12.3.2 Commands provided by package dependencies

In some cases a package’s build process will require the availability of executables not provided by the core system, a common example being autotools. Commands provided by dependencies are available in the following cases:

• In the src phases, any command provided by a package listed in DEPEND is available.
• In the pkg phases, at least one of the following conditions must be met:
  • Any command provided by a package listed in DEPEND is available.
  • Any command provided by a package listed in RDEPEND is available.

12.3.3 Ebuild-specific Commands

The following commands will always be available in the ebuild environment, provided by the package manager. Except where otherwise noted, they may be internal (shell functions or aliases) or external commands available in PATH; where this is not specified, ebuilds may not rely upon either behaviour.

Failure behaviour and related commands

DIE-ON-FAILURE

Where a command is listed as having EAPI dependent failure behaviour, a failure shall either result in a non-zero exit status or abort the build process, as determined by table 12.5.

The following commands affect this behaviour:

nonfatal

NONFATAL Executes the remainder of its arguments as a command, preserving the exit status. If this results in a command being called that would normally abort the build process due to a failure (but not due to an explicit die or assert call), instead a non-zero exit status shall be returned. Only in EAPIs listed in table 12.5 as supporting nonfatal.

Banned commands

BANNED-COMMANDS

Some commands are banned in some EAPIs. If a banned command is called, the package manager must abort the build process indicating an error.

Sandbox commands

These commands affect the behaviour of the sandbox. Each command takes a single directory as argument. Ebuilds must not run any of these commands once the current phase function has returned.

addread

Add a directory to the permitted read list.

addwrite

Add a directory to the permitted write list.

addpredict

Add a directory to the predict list. Any write to a location in this list will be denied, but will not trigger access violation messages or abort the build process.

adddeny

Add a directory to the deny list.

Package manager query commands

These commands are used to extract information about the host system. Ebuilds must not run any of these commands in parallel with any other package manager command. Ebuilds must not run any of these commands once the current phase function has returned.

has_version

Takes exactly one package dependency specification as an argument. Returns true if a package matching the atom is installed in ROOT, and false otherwise.

best_version

Takes exactly one package dependency specification as an argument. If a matching package is installed, prints the category, package name and version of the highest matching version.

Output commands

These commands display messages to the user. Unless otherwise stated, the entire argument list is used as a message, with backslash-escaped characters interpreted as for the echo -e command of bash, notably \t for a horizontal tab, \n for a new line, and \\ for a literal backslash. Ebuilds must not run any of these commands once the current phase function has returned. Unless otherwise noted, output may be sent to stdout, stderr or some other appropriate facility.

einfo

Displays an informational message.

einfon

Displays an informational message without a trailing newline.

elog

Displays an informational message of slightly higher importance. The package manager may choose to log elog messages by default where einfo messages are not, for example.

ewarn

Displays a warning message. Must not go to stdout.

eerror

Displays an error message. Must not go to stdout.

ebegin

Displays an informational message. Should be used when beginning a possibly lengthy process, and followed by a call to eend.

eend

Indicates that the process begun with an ebegin message has completed. Takes one fixed argument, which is a numeric return code, and an optional message in all subsequent arguments. If the first argument is 0, print a success indicator; otherwise, print the message followed by a failure indicator.

Error commands

These commands are used when an error is detected that will prevent the build process from completing. Ebuilds must not run any of these commands once the current phase function has returned.

die

Displays a failure message provided in its first and only argument, and then aborts the build process. die is not guaranteed to work correctly if called from a subshell environment.

assert

Checks the value of the shell’s pipe status variable, and if any component is non-zero (indicating failure), calls die with its first argument as a failure message.

Build commands

These commands are used during the src_compile and src_install phases to run the package’s build commands. Ebuilds must not run any of these commands once the current phase function has returned.

econf

Calls the program’s ./configure script. This is designed to work with GNU Autoconf-generated scripts. Any additional parameters passed to econf are passed directly to ./configure. econf will look in the current working directory for a configure script unless the ECONF_SOURCE environment variable is set, in which case it is taken to be the directory containing it. econf must pass the following options to the configure script:

ECONF-OPTIONS

• --prefix must default to ${EPREFIX}/usr unless overridden by econf’s caller.
• --mandir must be ${EPREFIX}/usr/share/man
• --infodir must be ${EPREFIX}/usr/share/info
• --datadir must be ${EPREFIX}/usr/share
• --sysconfdir must be ${EPREFIX}/etc
• --localstatedir must be ${EPREFIX}/var/lib
• --host must be the value of the CHOST environment variable.
• --libdir must be set according to Algorithm 9.
• --disable-dependency-tracking, if the EAPI is listed in table 12.7 as using it.

---

Table 12.7: Extra econf arguments for EAPIs

EAPI	--disable-dependency-tracking?
0	No
1	No
2	No
3	No
4	Yes

---

Note that the ${EPREFIX} component represents the same offset-prefix as described in Table 12.1. It facilitates offset-prefix installations which is supported by EAPIs listed in Table ??. When no offset-prefix installation is in effect, EPREFIX becomes the empty string, making the behaviour of econf equal for both offset-prefix supporting and agnostic EAPIs.

econf must be implemented internally—that is, as a bash function and not an external script. Should any portion of it fail, it must abort the build using die, unless run using nonfatal, in which case it must return non-zero exit status.

---

Algorithm 9: econf --libdir logic

 1:  let prefix=${EPREFIX}/usr
 2:  if the caller specified --prefix=$p then
 3:  let prefix=$p
 4:  end if
 5:  let libdir=
 6:  if the ABI environment variable is set then
 7:  let libvar=LIBDIR_$ABI
 8:  if the environment variable named by libvar is set then
 9:  let libdir=the value of the variable named by libvar
10:  end if
11:  end if
12:  if libdir is non-empty then
13:  pass --libdir=$prefix/$libdir to configure
14:  end if

---

emake

Calls the $MAKE program, or GNU make if the MAKE variable is unset. Any arguments given are passed directly to the make command, as are the user’s chosen MAKEOPTS. Arguments given to emake override user configuration. See also section 12.3.1. emake must be an external program and cannot be a function or alias—it must be callable from e.g. xargs. Failure behaviour is EAPI dependent as per section 12.3.3.

einstall

A shortcut for the command given in Listing 12.2. Any arguments given to einstall are passed verbatim to emake, as shown. Failure behaviour is EAPI dependent as per section 12.3.3.

The variable ED is defined as in Table 12.1 and depends on the use of an offset-prefix. When such offset-prefix is absent, ED is equivalent to D. ED is always available in EAPIs that support offset-prefix installations as listed in Table 12.3, hence EAPIs lacking offset-prefix support should use D instead of ED in the command given in Listing 12.2.

---

Listing 12.2: einstall command

emake \  
   prefix="${ED}"/usr \  
   mandir="${ED}"/usr/share/man \  
   infodir="${ED}"/usr/share/info \  
   libdir="${ED}"/usr/$(get_libdir) \  
   "$@" \  
   install  
  

---

Installation commands

These commands are used to install files into the staging area, in cases where the package’s make install target cannot be used or does not install all needed files. Except where otherwise stated, all filenames created or modified are relative to the staging directory including the offset-prefix ED in offset-prefix aware EAPIs, or just the staging directory D in offset-prefix agnostic EAPIs. These commands must all be external programs and not bash functions or aliases—that is, they must be callable from xargs. Ebuilds must not run any of these commands once the current phase function has returned.

dobin

Installs the given files into DESTTREE/bin, where DESTTREE defaults to /usr. Gives the files mode 0755 and transfers file ownership to the superuser or its equivalent on the system or installation at hand. For instance on Gentoo Linux in a non-offset-prefix installation this ownership is root:root, while on an offset-prefix aware installation this may be joe:users. Failure behaviour is EAPI dependent as per section 12.3.3.

doconfd

Installs the given config files into /etc/conf.d/, by default with file mode 0644. This can be overridden by setting INSOPTIONS with the insopts function. Failure behaviour is EAPI dependent as per section 12.3.3.

dodir

Creates the given directories, by default with file mode 0755. This can be overridden by setting DIROPTIONS with the diropts function. Failure behaviour is EAPI dependent as per section 12.3.3.

dodoc

DODOC Installs the given files into a subdirectory under /usr/share/doc/${PF}/ with file mode 0644. The subdirectory is set by the most recent call to docinto. If docinto has not yet been called, instead installs to the directory /usr/share/doc/${PF}/. For EAPIs listed in table 12.8 as supporting -r, if the first argument is -r, any subsequent arguments that are directories are installed recursively to the appropriate location; in any other case, it is an error for a directory to be specified. Failure behaviour is EAPI dependent as per section 12.3.3.

doenvd

Installs the given environment files into /etc/env.d/, by default with file mode 0644. This can be overridden by setting INSOPTIONS with the insopts function. Failure behaviour is EAPI dependent as per section 12.3.3.

doexe

Installs the given files into the directory specified by the most recent exeinto call, by default with file mode 0755. This can be overridden by setting EXEOPTIONS with the exeopts function. If exeinto has not yet been called, behaviour is undefined. Failure behaviour is EAPI dependent as per section 12.3.3.

dohard

Takes two parameters. Creates a hardlink from the second to the first. In EAPIs listed in table 12.6, this command is banned as per section 12.3.3. Failure behaviour is EAPI dependent as per section 12.3.3.

dohtml

Installs the given HTML files into a subdirectory under /usr/share/doc/$PF/. The subdirectory is html by default, but this can be overridden by setting the DOCDESTTREE variable with the docinto function. Files to be installed automatically are determined by extension and the default extensions are css, gif, htm, html, jpeg, jpg, js and png. These default extensions can be extended or reduced (see below). The options that can be passed to dohtml are as follows:

-r — enables recursion into directories.

-V — enables verbosity.

-A — adds file type extensions to the default list.

-a — sets file type extensions to only those specified.

-f — list of files that are able to be installed.

-x — list of directories that files will not be installed from (only used in conjunction with -r).

-p — sets a document prefix for installed files, not to be confused with the global offset-prefix.

Failure behaviour is EAPI dependent as per section 12.3.3.

It is undefined whether a failure shall occur if -r is not specified and a directory is encountered. Ebuilds must not rely upon any particular behaviour.

doinfo

Installs a GNU Info file into the /usr/share/info area with file mode 0644. Failure behaviour is EAPI dependent as per section 12.3.3.

doinitd

Installs the given initscript files into /etc/init.d, by default with file mode 0755. This can be overridden by setting EXEOPTIONS with the exeopts function. Failure behaviour is EAPI dependent as per section 12.3.3.

doins

DOINS Takes any number of files as arguments and installs them into INSDESTTREE, by default with file mode 0644. This can be overridden by setting INSOPTIONS with the insopts function. If the first argument is -r, then operates recursively, descending into any directories given. For EAPIs listed in table 12.9, doins must install symlinks as symlinks; for other EAPIs, behaviour is undefined if any symlink is encountered. Failure behaviour is EAPI dependent as per section 12.3.3.

dolib

For each argument, installs it into the appropriate library directory as determined by Algorithm 10, by default with file mode 0644. This can be overridden by setting LIBOPTIONS with the libopts function. Any symlinks are installed into the same directory as relative links to their original target. Failure behaviour is EAPI dependent as per section 12.3.3.

dolib.so

As for dolib except each file is installed with mode 0755.

dolib.a

As for dolib except each file is installed with mode 0644.

---

Algorithm 10: Determining the library directory

 1:  if CONF_LIBDIR_OVERRIDE is set in the environment then
 2:  return CONF_LIBDIR_OVERRIDE
 3:  end if
 4:  if CONF_LIBDIR is set in the environment then
 5:  let LIBDIR_default=CONF_LIBDIR
 6:  else
 7:  let LIBDIR_default=“lib”
 8:  end if
 9:  if ABI is set in the environment then
10:  let abi=ABI
11:  else if DEFAULT_ABI is set in the environment then
12:  let abi=DEFAULT_ABI
13:  else
14:  let abi=“default”
15:  end if
16:  return the value of LIBDIR_$abi

---

doman

Installs a man page into the appropriate subdirectory of /usr/share/man depending upon its apparent section suffix (e.g. foo.1 goes to /usr/share/man/man1/foo.1 with file mode 0644.

DOMAN-LANGS

In EAPIs listed in table 12.10 as supporting language codes, a man page with name of the formfoo.lang.1 shall go to /usr/share/man/lang/man1/foo.1, where lang refers to a pair of lower-case ASCII letters optionally followed by an underscore and a pair of upper-case ASCII letters. Failure behaviour is EAPI dependent as per section 12.3.3.

domo

Installs a .mo file with file mode 0644 into the appropriate subdirectory of DESTTREE/share/locale, generated by taking the basename of the file, removing the .* suffix, and appending /LC_MESSAGES. The name of the installed files is the package name with .mo appended. Failure behaviour is EAPI dependent as per section 12.3.3.

dosbin

As dobin, but installs to DESTTREE/sbin.

dosym

Creates a symbolic link named as for its second parameter, pointing to the first. If the directory containing the new link does not exist, creates it. Failure behaviour is EAPI dependent as per section 12.3.3.

fowners

Acts as for chown, but takes paths relative to the image directory. Failure behaviour is EAPI dependent as per section 12.3.3.

fperms

Acts as for chmod, but takes paths relative to the image directory. Failure behaviour is EAPI dependent as per section 12.3.3.

newbin

As for dobin, but takes two parameters. The first is the file to install; the second is the new filename under which it will be installed.

newconfd

As for doconfd, but takes two parameters as for newbin.

newdoc

As above, for dodoc.

newenvd

As above, for doenvd.

newexe

As above, for doexe.

newinitd

As above, for doinitd.

newins

As above, for doins.

newlib.a

As above, for dolib.a.

newlib.so

As above, for dolib.so.

newman

As above, for doman.

newsbin

As above, for dosbin.

keepdir

Creates a directory as for dodir, and an empty file whose name starts with .keep in that directory to ensure that the directory does not get removed by the package manager should it be empty at any point. Failure behaviour is EAPI dependent as per section 12.3.3.

Commands affecting install destinations

The following commands are used to set the various destination trees, all relative to ${ED} in offset-prefix aware EAPIs and relative to ${D} in offset-prefix agnostic EAPIs, used by the above installation commands. They must be shell functions or aliases, due to the need to set variables read by the above commands. Ebuilds must not run any of these commands once the current phase function has returned.

into

Sets the value of DESTTREE for future invocations of the above utilities. Creates the directory under ${ED} in offset-prefix aware EAPIs or under ${D} in offset-prefix agnostic EAPIs, using install -d with no additional options, if it does not already exist. Failure behaviour is EAPI dependent as per section 12.3.3.

insinto

Sets the value of INSDESTTREE for future invocations of the above utilities. May create the directory, as specified for into.

exeinto

Sets the install path for doexe and newexe. May create the directory, as specified for into.

docinto

Sets the install subdirectory for dodoc et al. May create the directory, as specified for into.

insopts

Sets the options passed by doins et al. to the install command.

diropts

Sets the options passed by dodir et al. to the install command.

exeopts

Sets the options passed by doexe et al. to the install command.

libopts

Sets the options passed by dolib et al. to the install command.

Commands affecting install compression

CONTROLLABLE-COMPRESS

In EAPIs listed in table 12.11 as supporting controllable compression, the package manager may optionally compress a subset of the files under the ED directory in offset-prefix aware EAPIs or the D directory in offset-prefix agnostic EAPIs. To control which directories may or may not be compressed, the package manager shall maintain two lists:

• An inclusion list, which initially contains /usr/share/doc, /usr/share/info and /usr/share/man.
• An exclusion list, which initially contains /usr/share/doc/${PF}/html.

The optional compression shall be carried out after src_install has completed, and before the execution of any subsequent phase function. For each item in the inclusion list, pretend it has the value of the ED variable in offset-prefix aware EAPIs or the D variable in offset-prefix agnostic EAPIs prepended, then:

• If it is a directory, act as if every file or directory immediately under this directory were in the inclusion list.
• If the item is a file, it may be compressed unless it has been excluded as described below.
• If the item does not exist, it is ignored.

Whether an item is to be excluded is determined as follows: For each item in the exclusion list, pretend it has the value of the ED variable in offset-prefix aware EAPIs or the D variable in offset-prefix agnostic EAPIs prepended, then:

• If it is a directory, act as if every file or directory immediately under this directory were in the exclusion list.
• If the item is a file, it shall not be compressed.
• If the item does not exist, it is ignored.

The package manager shall take appropriate steps to ensure that its compression mechanisms behave sensibly even if an item is listed in the inclusion list multiple times, if an item is a symlink, or if a file is already compressed.

The following commands may be used in src_install to alter these lists. It is an error to call any of these functions from any other phase.

docompress

If the first argument is -x, add each of its subsequent arguments to the exclusion list. Otherwise, add each argument to the inclusion list. Only available in EAPIs listed in table 12.11 as supporting docompress.

Use List Functions

These functions provide behaviour based upon set or unset use flags. Ebuilds must not run any of these commands once the current phase function has returned. Ebuilds must not run any of these functions in global scope.

If any of these functions is called with a flag value that is not included in IUSE_EFFECTIVE, either behaviour is undefined or it is an error as decided by table 12.12.

use

Returns shell true (0) if the first argument (a USE flag name) is enabled, false otherwise. If the flag name is prefixed with !, returns true if the flag is disabled, and false if it is enabled. It is guaranteed that this command is quiet.

usev

The same as use, but also prints the flag name if the condition is met.

useq

Deprecated synonym for use.

use_with

Has one-, two-, and three-argument forms. The first argument is a USE flag name, the second a configure option name (${opt}), defaulting to the same as the first argument if not provided, and the third is a string value (${value}), defaulting to nothing. If the USE flag is set, outputs --with-${opt}=${value} if the third argument was provided, and --with-${opt} otherwise. If the flag is not set, then it outputs --without-${opt}.

use_enable

Works the same as use_with(), but outputs --enable- or --disable- instead of --with- or --without-.

Text List Functions

These functions check whitespace-separated lists for a particular value.

has

Returns shell true (0) if the first argument (a word) is found in the list of subsequent arguments, false otherwise. Guaranteed quiet.

hasv

The same as has, but also prints the first argument if found.

hasq

Deprecated synonym for has.

Misc Commands

The following commands are always available in the ebuild environment, but don’t really fit in any of the above categories. Ebuilds must not run any of these commands once the current phase function has returned.

dosed

Takes any number of arguments, which can be files or sed expressions. For each argument, if it names, relative to ED (offset-prefix aware EAPIs) or D (offset-prefix agnostic EAPIs) a file which exists, then sed is run with the current expression on that file. Otherwise, the current expression is set to the text of the argument. The initial value of the expression is s:${ED}::g in offset-prefix aware EAPIs and s:${D}::g in offset-prefix agnostic EAPIs. In EAPIs listed in table 12.6, this command is banned as per section 12.3.3. Failure behaviour is EAPI dependent as per section 12.3.3.

unpack

Unpacks one or more source archives, in order, into the current directory. After unpacking, must ensure that all filesystem objects inside the current working directory (but not the current working directory itself) have permissions a+r,u+w,go-w and that all directories under the current working directory additionally have permissions a+x.

All arguments to unpack must be either a filename without path, in which case unpack looks in DISTDIR for the file, or start with the string ./, in which case unpack uses the argument as a path relative to the working directory.

Any unrecognised file format shall be skipped silently. If unpacking a supported file format fails, unpack shall abort the build process.

UNPACK-EXTENSIONS

Must be able to unpack the following file formats, if the relevant binaries are available:

• tar files (*.tar). Ebuilds must ensure that GNU tar installed.
• gzip-compressed tar files (*.tar.gz, *.tgz, *.tar.Z, *.tbz). Ebuilds must ensure that GNU gzip and GNU tar are installed.
• bzip2-compressed tar files (*.tar.bz2, *.tbz2, *.tar.bz). Ebuilds must ensure that bzip2 and GNU tar are installed.
• zip files (*.zip, *.ZIP, *.jar). Ebuilds must ensure that Info-ZIP Unzip is installed.
• gzip files (*.gz, *.Z, *.z). Ebuilds must ensure that GNU gzip is installed.
• bzip2 files (*.bz, *.bz2). Ebuilds must ensure that bzip2 is installed.
• 7zip files (*.7z, *.7Z). Ebuilds must ensure that P7ZIP is installed.
• rar files (*.rar, *.RAR). Ebuilds must ensure that RARLAB’s unrar is installed.
• LHA archives (*.LHA, *.LHa, *.lha, *.lhz). Ebuilds must ensure that the lha program is installed.
• ar archives (*.a). Ebuilds must ensure that GNU binutils is installed.
• deb packages (*.deb). Ebuilds must ensure that the deb2targz program is installed on those platforms where the GNU binutils ar program is not available and the installed ar program is incompatible with GNU archives. Otherwise, ebuilds must ensure that GNU binutils is installed.
• lzma-compressed files (*.lzma). Ebuilds must ensure that LZMA Utils is installed.
• lzma-compressed tar files (*.tar.lzma). Ebuilds must ensure that LZMA Utils and GNU tar are installed.
• xz-compressed files (*.xz). Ebuilds must ensure that XZ Utils is installed. Only for EAPIs listed in table 12.13 as supporting xz.
• xz-compressed tar files (*.tar.xz). Ebuilds must ensure that XZ Utils and GNU tar are installed. Only for EAPIs listed in table 12.13 as supporting xz.

It is up to the ebuild to ensure that the relevant external utilities are available, whether by being in the system set or via dependencies.

---

Table 12.13: unpack extensions for EAPIs

EAPI	.xz and .tar.xz?
0	No
1	No
2	No
3	Yes
4	Yes

---

inherit

See section 11.1.

default

DEFAULT-FUNC Calls the default_ function for the current phase (see section 10.1.17). Must not be called if the default_ function does not exist for the current phase in the current EAPI. Only available in EAPIs listed in table 12.14.

Debug Commands

The following commands are available for debugging. Normally all of these commands should be no ops; a package manager may provide a special debug mode where these commands instead do something. Ebuilds must not run any of these commands once the current phase function has returned.

debug-print

If in a special debug mode, the arguments should be outputted or recorded using some kind of debug logging.

debug-print-function

Calls debug-print with $1: entering function as the first argument and the remaining arguments as additional arguments.

debug-print-section

Calls debug-print with now in section $*.

Reserved Commands and Variables

Except where documented otherwise, all functions and variables that contain any of the following strings (ignoring case) are reserved for package manager use and may not be used or relied upon by ebuilds:

• abort
• dyn
• ebuild
• hook
• paludis
• portage
• prep

12.4 The state of the system between functions

For the sake of this section:

• Variancy is any package manager action that modifies either ROOT or / in any way that isn’t merely a simple addition of something that doesn’t alter other packages. This includes any non-default call to any pkg phase function except pkg_setup, a merge of any package or an unmerge of any package.
• As an exception, changes to DISTDIR do not count as variancy.
• The pkg_setup function may be assumed not to introduce variancy. Thus, ebuilds must not perform variant actions in this phase.

The following exclusivity and invariancy requirements are mandated:

• No variancy shall be introduced at any point between a package’s pkg_setup being started up to the point that that package is merged, except for any variancy introduced by that package.
• There must be no variancy between a package’s pkg_setup and a package’s pkg_postinst, except for any variancy introduced by that package.
• Any non-default pkg phase function must be run exclusively.
• Each phase function must be called at most once during the build process for any given package.

Chapter 13
Merging and Unmerging

Note: In this chapter, file and regular file have their Unix meanings.

13.1 Overview

The merge process merges the contents of the D directory onto the filesystem under ROOT. This is not a straight copy; there are various subtleties which must be addressed.

The unmerge process removes an installed package’s files. It is not covered in detail in this specification.

13.2 Directories

Directories are merged recursively onto the filesystem. The method used to perform the merge is not specified, so long as the end result is correct. In particular, merging a directory may alter or remove the source directory under D.

Ebuilds must not attempt to merge a directory on top of any existing file that is not either a directory or a symlink to a directory.

13.2.1 Permissions

The owner, group and mode (including set*id and sticky bits) of the directory must be preserved, except as follows:

• Any directory owned by the user used to perform the build must become owned by the root user.
• Any directory whose group is the primary group of the user used to perform the build must have its group be that of the root user.

On SELinux systems, the SELinux context must also be preserved. Other directory attributes, including modification time, may be discarded.

13.2.2 Empty Directories

Behaviour upon encountering an empty directory is undefined. Ebuilds must not attempt to install an empty directory.

13.3 Regular Files

Regular files are merged onto the filesystem (but see the notes on configuration file protection, below). The method used to perform the merge is not specified, so long as the end result is correct. In particular, merging a regular file may alter or remove the source file under D.

Ebuilds must not attempt to merge a regular file on top of any existing file that is not either a regular file or a symlink to a regular file.

13.3.1 Permissions

The owner, group and mode (including set*id and sticky bits) of the file must be preserved, except as follows:

• Any file owned by the user used to perform the build must become owned by the root user.
• Any file whose group is the primary group of the user used to perform the build must have its group be that of the root user.
• The package manager may reduce read and write permissions on executable files that have a set*id bit set.

On SELinux systems, the SELinux context must also be preserved. Other file attributes may be discarded.

13.3.2 File modification times

MTIME-PRESERVE

In EAPIs listed in table 13.1, the package manager must preserve modification times of regular files. This includes files being compressed before merging. Exceptions to this are files newly created by the package manager and binary object files being stripped of symbols.

When preserving, the seconds part of every regular file’s mtime must be preserved exactly. The sub-second part must either be set to zero, or set to the greatest value supported by the operating system and filesystem that is not greater than the sub-second part of the original time.

For any given destination filesystem, the package manager must ensure that for any two preserved files a, b in that filesystem the relation mtime(a) ≤ mtime(b) still holds, if it held under the original image directory.

In other EAPIs, the behaviour with respect to file modification times is undefined.

13.3.3 Configuration File Protection

The package manager must provide a means to prevent user configuration files from being overwritten by any package updates. The profile variables CONFIG_PROTECT and CONFIG_PROTECT_MASK (section 5.3) control the paths for which this must be enforced.

In order to ensure interoperability with configuration update tools, the following scheme must be used by all package managers when merging any regular file:

1.

If the directory containing the file to be merged is not listed in CONFIG_PROTECT, and is not a subdirectory of any such directory, and if the file is not listed in CONFIG_PROTECT, the file is merged normally.

2.

If the directory containing the file to be merged is listed in CONFIG_PROTECT_MASK, or is a subdirectory of such a directory, or if the file is listed in CONFIG_PROTECT_MASK, the file is merged normally.

3.

If no existing file with the intended filename exists, or the existing file has identical content to the one being merged, the file is installed normally.

4.

Otherwise, prepend the filename with ._cfg0000_. If no file with the new name exists, then the file is merged with this name.

5.

Otherwise, increment the number portion (to form ._cfg0001_<name>) and repeat step 4. Continue this process until a usable filename is found.

6.

If 9999 is reached in this way, behaviour is undefined.

13.4 Symlinks

Symlinks are merged as symlinks onto the filesystem. The link destination for a merged link shall be the same as the link destination for the link under D, except as noted below. The method used to perform the merge is not specified, so long as the end result is correct; in particular, merging a symlink may alter or remove the symlink under D.

Ebuilds must not attempt to merge a symlink on top of a directory.

13.4.1 Rewriting

Any absolute symlink whose link starts with D must be rewritten with the leading D removed. The package manager should issue a notice when doing this.

13.5 Hard links

A hard link may be merged either as a single file with links or as multiple independent files.

13.6 Other Files

Ebuilds must not attempt to install any other type of file (FIFOs, device nodes etc).

Chapter 14
Metadata Cache

14.1 Directory Contents

The profiles/metadata/cache directory, if it exists, contains directories whose names are the same as categories in the repository. Each subdirectory may optionally contain one file per package version in that category, named <package>-<version>, in the format described below.

The metadata cache may be incomplete or non-existent, and may contain additional bogus entries.

14.2 Cache File Format

Each cache file contains the textual values of various metadata keys, one per line, in the following order. Other lines may be present following these; their meanings are not defined here.

1.

Build-time dependencies (DEPEND)

2.

Run-time dependencies (RDEPEND)

3.

Slot (SLOT)

4.

Source tarball URIs (SRC_URI)

5.

RESTRICT

6.

Package homepage (HOMEPAGE)

7.

Package license (LICENSE)

8.

Package description (DESCRIPTION)

9.

Package keywords (KEYWORDS)

10.

Inherited eclasses (INHERITED)

11.

Use flags that this package respects (IUSE)

12.

No longer used; this line is to be ignored.

13.

Post dependencies (PDEPEND)

14.

Old-style virtuals provided by this package (PROVIDE)

15.

The ebuild API version to which this package conforms (EAPI)

16.

Properties (PROPERTIES). In some EAPIs, may optionally be blank, regardless of ebuild metadata; see table 8.2.

17.

Defined phases (DEFINED_PHASES). In some EAPIs, may optionally be blank, regardless of ebuild metadata; see table 8.4.

18.

Blank lines to pad the file to 22 lines long

Future EAPIs may define new variables, remove existing variables, change the line number or format used for a particular variable, add or reduce the total length of the file and so on. Any future EAPI that uses this cache format will continue to place the EAPI value on line 15 if such a concept makes sense for that EAPI, and will place a value that is clearly not a supported EAPI on line 15 if it does not.

Chapter 15
Glossary

This section contains explanations of some of the terms used in this document whose meaning may not be immediately obvious.

qualified package name

A package name along with its associated category. For example, app-editors/vim is a qualified package name.

old-style virtual

An old-style virtual is a psuedo-package which exists if it is listed in an ebuild’s PROVIDE variable. See chapter 6.

new-style virtual

A new-style virtual is a normal package in the virtual category which installs no files and uses its dependency requirements to pull in a ‘provider’. This is more flexible than the old-style virtuals described above, and requires no special package manager code.

stand-alone repository

An (ebuild) repository which is intended to function on its own as the only, or primary, repository on a system. Contrast with slave repository below.

slave repository, non-stand-alone repository

An (ebuild) repository which is not complete enough to function on its own, but needs one or more master repositories to satisfy dependencies and provide repository-level support files. Known in Portage as an overlay.

master repository

See above.

Appendix A
metadata.xml

The metadata.xml file is used to contain extra package- or category-level information beyond what is stored in ebuild metadata. Its exact format is strictly beyond the scope of this document, and is described in the DTD file located at http://www.gentoo.org/dtd/metadata.dtd.

Appendix B
Unspecified Items

The following items are not specified by this document, and must not be relied upon by ebuilds. This is, of course, an incomplete list—it covers only the things that the authors know have been abused in the past.

• The FEATURES variable. This is Portage specific.
• Similarly, any PORTAGE_ variable not explicitly listed.
• Any Portage configuration file.
• The VDB (/var/db/pkg). Ebuilds must not access this or rely upon it existing or being in any particular format.
• The portageq command. The has_version and best_version commands are available as functions.
• The emerge command.
• Binary packages.
• The PORTDIR_OVERLAY variable, and overlay behaviour in general.

Appendix C
Historical Curiosities

The items described in this chapter are included for information only. They were deprecated or abandoned long before EAPI was introduced. Ebuilds must not use these features, and package managers should not be changed to support them.

C.1 If-else use blocks

Historically, Portage supported if-else use conditionals, as shown by listing C.1. The block before the colon would be taken if the condition was met, and the block after the colon would be taken if the condition was not met.

This feature was deprecated and removed from the tree long before the introduction of EAPI.

C.2 cvs Versions

Portage has very crude support for CVS packages. The package foo could contain a file named foo-cvs.1.2.3.ebuild. This version would order higher than any non-CVS version (including foo-2.ebuild). This feature has not seen real world use and breaks versioned dependencies, so it must not be used.

C.3 use.defaults

The use.defaults file in the profile directory was used to implement ‘autouse’—switching USE flags on or off depending upon which packages are installed. It was deprecated long ago and finally removed in 2009.

Appendix D
Feature Availability by EAPI

Note: This chapter is informative and for convenience only. Refer to the main text for specifics.

Appendix E
Differences Between EAPIs

Note: This chapter is informative and for convenience only. Refer to the main text for specifics.

EAPI 0

EAPI 0 is the base EAPI.

EAPI 1

EAPI 1 is EAPI 0 with the following changes:

• IUSE defaults, IUSE-DEFAULTS on page 74.
• Slot dependencies, SLOT-DEPS on page 104.
• Different src_compile implementation, SRC-COMPILE-1 on page 124.

EAPI 2

EAPI 2 is EAPI 1 with the following changes:

• SRC_URI arrows, SRC-URI-ARROWS on page 106.
• Use dependencies, USE-DEPS on page 95.
• ! and !! blockers, BANG-STRENGTH on page 101.
• src_prepare, SRC-PREPARE on page 116.
• src_configure, SRC-CONFIGURE on page 119.
• Different src_compile implementation, SRC-COMPILE-2 on page 125.
• default_ phase functions for phases pkg_nofetch, src_unpack, src_prepare, src_configure, src_compile and src_test; DEFAULT-PHASE-FUNCS on page 137.
• doman languages support, DOMAN-LANGS on page 185.
• default function, DEFAULT-FUNC on page 204.