EBUILD(5)

NAME
ebuild - the internal format, variables, and functions in an ebuild script

DESCRIPTION
The ebuild(1) program accepts a single ebuild script as an argument. This script contains variables and commands that specify how to download, unpack, patch, compile, install and merge a particular software package from its original sources. In addition to all of this, the ebuild script can also contain pre/post install/remove commands, as required. All ebuild scripts are written in bash.

EXAMPLES
Here's a simple example ebuild:
# Copyright 1999-2007 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $
inherit some_eclass another_eclass
DESCRIPTION="Super-useful stream editor (sed)"
HOMEPAGE="http://www.gnu.org/software/sed/sed.html"
SRC_URI="ftp://alpha.gnu.org/pub/gnu/sed/${P}.tar.gz"
LICENSE="GPL-2"
SLOT="0"
KEYWORDS="~x86"
IUSE=""
DEPEND="virtual/libc"
RDEPEND="virtual/libc"
src_compile() {
	econf || die "could not configure"
	emake || die "emake failed"
}
src_install() {
	into /usr
	doinfo doc/sed.info
	doman doc/sed.1
	into /
	dobin sed/sed || die "dobin sed failed"
	dodir /usr/bin
	dosym /bin/sed /usr/bin/sed
	dodoc NEWS README* THANKS TODO AUTHORS BUGS ANNOUNCE
}

VARIABLES

MISC USAGE NOTES
    - All variables defined in make.conf(5) are available for use in ebuilds (such as the PORTAGE* and PORTDIR* variables)
    - When assigning values to variables in ebuilds, you cannot have a space between the variable name and the equal sign.

P   This variable contains the package name without the ebuild revision. This variable must NEVER be modified.
    xfree-4.2.1-r2.ebuild --> $P=='xfree-4.2.1'

PN  Contains the name of the script without the version number.
    xfree-4.2.1-r2.ebuild --> $PN=='xfree'

PV  Contains the version number without the revision.
    xfree-4.2.1-r2.ebuild --> $PV=='4.2.1'

PR  Contains the revision number or 'r0' if no revision number exists.
    xfree-4.2.1-r2.ebuild --> $PR=='r2'

PVR Contains the version number with the revision.
    xfree-4.2.1-r2.ebuild --> $PVR=='4.2.1-r2'

PF  Contains the full package name [PN]-[PVR]
    xfree-4.2.1-r2.ebuild --> $PF=='xfree-4.2.1-r2'

CATEGORY
    Contains the package category name.

A   Contains all source files required for the package. This variable must not be defined. It is autogenerated from the SRC_URI variable.

WORKDIR = "${PORTAGE_TMPDIR}/portage/${CATEGORY}/${PF}/work"
    Contains the path to the package build root. Do not modify this variable.

FILESDIR = "${PORTDIR}/${CATEGORY}/${PN}/files"
    Contains the path to the 'files' sub folder in the package specific location in the portage tree. Do not modify this variable.

S = "${WORKDIR}/${P}"
    Contains the path to the temporary build directory. This variable is used by the functions src_compile and src_install. Both are executed with S as the current directory. This variable may be modified to match the extraction directory of a tarball for the package.

T = "${PORTAGE_TMPDIR}/portage/${CATEGORY}/${PF}/temp"
    Contains the path to a temporary directory. You may use this for whatever you like.

D = "${PORTAGE_TMPDIR}/portage/${CATEGORY}/${PF}/image"
    Contains the path to the temporary install directory. Every write operation that does not involve the helper tools and functions (found below) should be prefixed with ${D}. Do not modify this variable.

PORTAGE_LOG_FILE
    Contains the path of the build log. If PORT_LOGDIR variable is unset then PORTAGE_LOG_FILE="${T}/build.log".

ROOT = "/"
    Contains the path that portage should use as the root of the live filesystem. When packages wish to make changes to the live filesystem, they should do so in the tree prefixed by ${ROOT}. Do not modify this variable.

DESCRIPTION = "A happy little package"
    Should contain a short description of the package.

SRC_URI = "http://happy.com/little/${P}.tar.gz"
    Contains a list of URI's for the required source files. It can contain multiple URI's for a single source file. The list is processed in order if the file was not found on any of the GENTOO_MIRRORS.

HOMEPAGE = "http://happy.com/"
    Should contain a list of URL's for the sources main sites and other further package dependent information.

KEYWORDS = [-~][x86,ppc,sparc,mips,alpha,arm,hppa]
    Should contain appropriate list of arches that the ebuild is know to work/not work. By default if you do not know if an ebuild runs under a particular arch simply omit that KEYWORD. If the ebuild will not work on that arch include it as -ppc for example. If the ebuild is being submitted for inclusion, it must have ~arch set for architectures where it has been PROVEN TO WORK. (Packages KEYWORDed this way may be unmasked for testing by setting ACCEPT_KEYWORDS="~arch" on the command line, or in make.conf(5)) For an authoritative list please review /usr/portage/profiles/arch.list. Please keep this list in alphabetical order.

SLOT
    This sets the SLOT for packages that may need to have multiple versions co-exist. By default you should set SLOT="0". If you are unsure, then do not fiddle with this until you seek some guidance from some guru. This value should NEVER be left undefined.

LICENSE
    This should be a space delimited list of licenses that the package falls under. This _must_ be set to a matching license in /usr/portage/licenses/. If the license does not exist in portage yet, you must add it first.

IUSE
    This should be a list of any and all USE flags that are leveraged within your build script. The only USE flags that should not be listed here are arch related flags (see KEYWORDS).

DEPEND
    This should contain a list of all packages that are required for the program to compile.

    DEPEND Atoms
        A depend atom is simply a dependency that is used by portage when calculating relationships between packages. Please note that if the atom has not already been emerged, then the latest version available is matched.

        Atom Bases
            The base atom is just a full category/packagename. Hence, these are base atoms:
            sys-apps/sed
            sys-libs/zlib
            net-misc/dhcp

        Atom Versions
            It is nice to be more specific and say that only certain versions of atoms are acceptable. Note that versions must be combined with a prefix (see below). Hence you may add a version number as a postfix to the base:
            sys-apps/sed-4.0.5
            sys-libs/zlib-1.1.4-r1
            net-misc/dhcp-3.0_p2
            Versions are normally made up of two or three numbers separated by periods, such as 1.2 or 4.5.2. This string may be followed by a character such as 1.2a or 4.5.2z. Note that this letter is not meant to indicate alpha, beta, etc... status. For that, use the optional suffix; either _alpha, _beta, _pre (pre-release), _rc (release candidate), or _p (patch). This means for the 3rd pre-release of a package, you would use something like 1.2_pre3.

        Atom Prefix Operators [> >= = <= <]
            Sometimes you want to be able to depend on general versions rather than specifying exact versions all the time. Hence we provide standard boolean operators:
            >media-libs/libgd-1.6
            >=media-libs/libgd-1.6
            =media-libs/libgd-1.6
            <=media-libs/libgd-1.6
            <media-libs/libgd-1.6

        Extended Atom Prefixes [!~] and Postfixes [*]
            Now to get even fancier, we provide the ability to define blocking packages and version range matching. Also note that these extended prefixes/postfixes may be combined in any way with the atom classes defined above. Here are some common examples you may find in the portage tree:
            !app-text/dos2unix
            =dev-libs/glib-2*
            !=net-fs/samba-2*
            ~net-libs/libnet-1.0.2a
            ! means block packages from being installed at the same time.
            * means match any version of the package so long as the specified base is matched. So with a version of '2*', we can match '2.1', '2.2', '2.2.1', etc... and not match version '1.0', '3.0', '4.1', etc...
            ~ means match any revision of the base version specified. So in the above example, we would match versions '1.0.2a', '1.0.2a-r1', '1.0.2a-r2', etc...

    Dynamic DEPENDs
        Sometimes programs may depend on different things depending on the USE variable. Portage offers a few options to handle this. Note that when using the following syntaxes, each case is considered as 1 Atom in the scope it appears. That means that each Atom both conditionally include multiple Atoms and be nested to an infinite depth.

        usevar? ( DEPEND Atom )
            To include the jpeg library when the user has jpeg in USE, simply use the following syntax:
            jpeg? ( media-libs/jpeg )

        !usevar? ( Atom )
            If you want to include a package only if the user does not have a certain option in their USE variable, then use the following syntax:
            !nophysfs? ( dev-games/physfs )
            This is often useful for those times when you want to want to add optional support for a feature and have it enabled by default.

        usevar? ( Atom if true ) !usevar? ( Atom if false )
            For functionality like the tertiary operator found in C you must use two statements, one normal and one inverted. If a package uses GTK2 or GTK1, but not both, then you can handle that like this:
            gtk2? ( =x11-libs/gtk+-2* ) !gtk2? ( =x11-libs/gtk+-1* )
            That way the default is the superior GTK2 library.

        || ( Atom Atom ... )
            When a package can work with a few different packages but a virtual is not appropriate, this syntax can easily be used.
            || (
            app-games/unreal-tournament
            app-games/unreal-tournament-goty
            )
            Here we see that unreal-tournament has a normal version and it has a goty version. Since they provide the same base set of files, another package can use either. Adding a virtual is inappropriate due to the small scope of it.
            Another good example is when a package can be built with multiple video interfaces, but it can only ever have just one.
            || (
            sdl? ( media-libs/libsdl )
            svga? ( media-libs/svgalib )
            opengl? ( virtual/opengl )
            ggi? ( media-libs/libggi )
            virtual/x11
            )
            Here only one of the packages will be chosen, and the order of preference is determined by the order in which they appear. So sdl has the best chance of being chosen, followed by svga, then opengl, then ggi, with a default of X if the user does not specify any of the previous choices.

RDEPEND
    This should contain a list of all packages that are required for this program to run (aka runtime depend). If this is not set, then it defaults to the value of DEPEND.
    You may use the same syntax to vary dependencies as seen above in DEPEND.

PDEPEND
    This should contain a list of all packages that will have to be installed after the program has been merged.
    You may use the same syntax to vary dependencies as seen above in DEPEND.

RESTRICT = [strip,mirror,fetch,userpriv]
    This should be a space delimited list of portage features to restrict.
    binchecks
        Disable all QA checks for binaries. This should ONLY be used in packages for which binary checks make no sense (linux-headers and kernel-sources, for example, can safely be skipped since they have no binaries). If the binary checks need to be skipped for other reasons (such as proprietary binaries), see the QA CONTROL VARIABLES section for more specific exemptions.
    confcache
        Prevent econf from using confcache.
    fetch
        like mirror but the files will not be fetched via SRC_URI either.
    mirror
        files in SRC_URI will not be downloaded from the GENTOO_MIRRORS.
    primaryuri
        fetch from URL's in SRC_URI before GENTOO_MIRRORS.
    strip
        final binaries/libraries will not be stripped of debug symbols.
    test
        do not run src_test even if user has FEATURES=test.
    userpriv
        Disables userpriv for specific packages.

PROVIDE = "virtual/TARGET"
    This variable should only be used when a package provides a virtual target. For example, blackdown-jdk and sun-jdk provide virtual/jdk. This allows for packages to depend on virtual/jdk rather than on blackdown or sun specifically.

QA CONTROL VARIABLES

USAGE NOTES
    Several QA variables are provided which allow an ebuild to manipulate some of the QA checks performed by portage. Use of these variables in ebuilds should be kept to an absolute minimum otherwise they defeat the purpose of the QA checks, and their use is subject to agreement of the QA team. They are primarily intended for use by ebuilds that install closed-source binary objects that cannot be altered.
    Note that objects that violate these rules may fail on some architectures.

QA_TEXTRELS
    This variable can be set to a list of file paths, relative to the image directory, of files that contain text relocations that cannot be eliminated. The paths may contain regular expressions.
    This variable is intended to be used on closed-source binary objects that cannot be altered.

QA_EXECSTACK
    This should contain a list of file paths, relative to the image directory, of objects that require executable stack in order to run. The paths may contain regular expressions.
    This variable is intended to be used on objects that truly need executable stack (i.e. not those marked to need it which in fact do not).

QA_WX_LOAD
    This should contain a list of file paths, relative to the image directory, of files that contain writable and executable segments. These are rare. The paths may contain regular expressions.

PORTAGE DECLARATIONS

inherit
    Inherit is portage's maintenance of extra classes of functions that are external to ebuilds and provided as inheritable capabilities and data. They define functions and set data types as drop-in replacements, expanded, and simplified routines for extremely common tasks to streamline the build process. Inherit may only be called once in an ebuild and it may never be wrapped within any conditionals of any kind. Specification of the eclasses contains only their name and not the .eclass extension. Also note that the inherit statement must come before other variable declarations.

FUNCTIONS

pkg_nofetch
    If you turn on fetch in RESTRICT, then this function will be run when the files in SRC_URI cannot be found. Useful for displaying information to the user on *how* to obtain said files. All you have to do is output a message and let the function return. Do not end the function with a call to die.

pkg_setup
    This function can be used if the package needs specific setup actions or checks to be preformed before anything else.
    Initial working directory of ${PORTAGE_TMPDIR}.

src_unpack
    This function is used to unpack all the sources in A to WORKDIR. If not defined in the ebuild script it calls unpack ${A}. Any patches and other pre configure/compile modifications should be done here.
    Initial working directory of $WORKDIR.

src_compile
    All necessary steps for configuration and compilation should be done in here.
    Initial working directory of $S.

src_test
    Run all package specific test cases. The default is to run 'make check' followed 'make test'.
    Initial working directory of $S.

src_install
    Should contain everything required to install the package in the temporary install directory.
    Initial working directory of $S.

pkg_preinst pkg_postinst
    All modifications required on the live-filesystem before and after the package is merged should be placed here. Also commentary for the user should be listed here as it will be displayed last.
    Initial working directory of $PWD.

pkg_prerm pkg_postrm
    Like the pkg_*inst functions but for unmerge.
    Initial working directory of $PWD.

pkg_config
    This function should contain optional basic configuration steps.
    Initial working directory of $PWD.

HELPER FUNCTIONS: GENERAL

die [reason]
    Causes the current emerge process to be aborted. The final display will include reason.

use <USE item>
    If USE item is in the USE variable, the function will silently return 0 (aka shell true). If USE item is not in the USE variable, the function will silently return 1 (aka shell false). usev is a verbose version of use.

    Example:
        if use gnome ; then
        	guiconf="--enable-gui=gnome --with-x"
        elif use gtk ; then
        	guiconf="--enable-gui=gtk --with-x"
        elif use X ; then
        	guiconf="--enable-gui=athena --with-x"
        else
        	# No gui version will be built
        	guiconf=""
        fi

use_with <USE item> [configure name] [configure opt]
    Useful for creating custom options to pass to a configure script. If USE item is in the USE variable and a configure opt is specified, then the string --with-[configure name]=[configure opt] will be echoed. If configure opt is not specified, then just --with-[configure name] will be echoed. If USE item is not in the USE variable, then the string --without-[configure name] will be echoed. If configure name is not specified, then USE item will be used in its place.

    Examples:
        USE="opengl"
        myconf=$(use_with opengl)
        (myconf now has the value "--with-opengl")
        USE="jpeg"
        myconf=$(use_with jpeg libjpeg)
        (myconf now has the value "--with-libjpeg")
        USE=""
        myconf=$(use_with jpeg libjpeg)
        (myconf now has the value "--without-libjpeg")
        USE="sdl"
        myconf=$(use_with sdl SDL all-plugins)
        (myconf now has the value "--with-SDL=all-plugins")

use_enable <USE item> [configure name] [configure opt]
    Same as use_with above, except that the configure options are --enable- instead of --with- and --disable- instead of --without-.

has <item> <item list>
    If item is in item list, then item is echoed and has returns 0. Otherwise, nothing is echoed and 1 is returned. As indicated with use, there is a non-echoing version hasq. Please use hasq in all places where output is to be disregarded. Never use the output for calculation.
    The item list is delimited by the IFS variable. This variable has a default value of ' ', or a space. It is a bash(1) setting.

has_version <category/package-version>
    Check to see if category/package-version is installed on the system. The parameter accepts all values that are acceptable in the DEPEND variable. The function returns 0 if category/package-version is installed, 1 otherwise.

best_version <package name>
    This function will look up package name in the database of currently installed programs and echo the "best version" of the package that is currently installed.

    Example:
        VERINS="$(best_version net-ftp/glftpd)"
        (VERINS now has the value "net-ftp/glftpd-1.27" if glftpd-1.27 is installed)

HELPER FUNCTIONS: OUTPUT

einfo "disposable message"
    Same as elog, but should be used when the message isn't important to the user (like progress or status messages during the build process).

elog "informative message"
    If you need to display a message that you wish the user to read and take notice of, then use elog. It works just like echo(1), but adds a little more to the output so as to catch the user's eye. The message will also be logged by portage for later review.

ewarn "warning message"
    Same as einfo, but should be used when showing a warning to the user.

eerror "error message"
    Same as einfo, but should be used when showing an error to the user.

ebegin "helpful message"
    Like einfo, we output a helpful message and then hint that the following operation may take some time to complete. Once the task is finished, you need to call eend.

eend <status> ["error message"]
    Followup the ebegin message with an appropriate "OK" or "!!" (for errors) marker. If status is non-zero, then the additional error message is displayed.

HELPER FUNCTIONS: UNPACK

unpack <source> [list of more sources]
    This function uncompresses and/or untars a list of sources into the current directory. The function will append source to the DISTDIR variable.

HELPER FUNCTIONS: COMPILE

econf [configure options]
    This is used as a replacement for configure. Performs:
    configure \
    	--prefix=/usr \
    	--host=${CHOST} \
    	--mandir=/usr/share/man \
    	--infodir=/usr/share/info \
    	--datadir=/usr/share \
    	--sysconfdir=/etc \
    	--localstatedir=/var/lib \
    	${EXTRA_ECONF} \
    	configure options
    Note that the EXTRA_ECONF is for users only, not for ebuild writers. If you wish to pass more options to configure, just pass the extra arguements to econf.

emake [make options]
    This is used as a replacement for make. Performs 'make ${MAKEOPTS} make options' (as set in /etc/make.globals), default is MAKEOPTS="-j2". ***warning***
    if you are going to use emake, make sure your build is happy with parallel makes (make -j2). It should be tested thoroughly as parallel makes are notorious for failing _sometimes_ but not always. If you determine that your package fails to build in parallel, and you are unable to resolve the issue, then you should run 'emake -j1' instead of 'make'.

HELPER FUNCTIONS: INSTALL

einstall [make options]
    This is used as a replacement for make install. Performs:
    make \
    	prefix=${D}/usr \
    	datadir=${D}/usr/share \
    	infodir=${D}/usr/share/info \
    	localstatedir=${D}/var/lib \
    	mandir=${D}/usr/share/man \
    	sysconfdir=${D}/etc \
    	${EXTRA_EINSTALL} \
    	make options \
    	install
    Please do not use this in place of 'emake install DESTDIR=${D}'. That is the preferred way of installing make-based packages. Also, do not utilize the EXTRA_EINSTALL variable since it is for users.
prepall
prepalldocs
prepallinfo
prepallman
prepallstrip
    Useful for when a package installs into ${D} via scripts (i.e. makefiles). If you want to be sure that libraries are executable, aclocal files are installed into the right place, doc/info/man files are all compressed, and that executables are all stripped of debugging symbols, then use these suite of functions.
    prepall:
        Runs prepallman, prepallinfo, prepallstrip, sets libraries +x, and then checks aclocal directories. Please note this does *not* run prepalldocs.
    prepalldocs:
        Compresses all doc files in ${D}/usr/share/doc.
    prepallinfo:
        Compresses all info files in ${D}/usr/share/info.
    prepallman:
        Compresses all man files in ${D}/usr/share/man.
    prepallstrip:
        Strips all executable files of debugging symboles. This includes libraries.
prepinfo [dir]
prepman [dir]
prepstrip [dir]
    Similiar to the prepall functions, these are subtle in their differences.
    prepinfo:
        If a dir is not specified, then prepinfo will assume the dir usr. prepinfo will then compress all the files in ${D}/dir/info.
    prepman:
        If a dir is not specified, then prepman will assume the dir usr. prepman will then compress all the files in ${D}/dir/man/*/.
    prepstrip:
        All the files found in ${D}/dir will be stripped. You may specify multiple directories.

dosed "s:orig:change:g" <filename>
    Performs sed (including cp/mv filename) on filename.
    'dosed "s:/usr/local:/usr:g" /usr/bin/some-script' runs sed on ${D}/usr/bin/some-script

dodir <path>
    Creates a directory inside of ${D}.
    'dodir /usr/lib/apache' creates ${D}/usr/lib/apache. Note that the do* functions will run dodir for you.

diropts [options for install(1)]
    Can be used to define options for the install function used in dodir. The default is -m0755.

into <path>
    Sets the root (DESTTREE) for other functions like dobin, dosbin, doman, doinfo, dolib.
    The default root is /usr.

keepdir <path>
    Tells portage to leave a directory behind even if it is empty. Functions the same as dodir.

dobin <binary> [list of more binaries]
    Installs a binary or a list of binaries into DESTTREE/bin. Creates all necessary dirs.

dosbin <binary> [list of more binaries]
    Installs a binary or a list of binaries into DESTTREE/sbin. Creates all necessary dirs.

doinitd <init.d script> [list of more init.d scripts]
    Install Gentoo init.d scripts. They will be installed into the correct location for Gentoo init.d scripts (/etc/init.d/). Creates all necessary dirs.

doconfd <conf.d file> [list of more conf.d file]
    Install Gentoo conf.d files. They will be installed into the correct location for Gentoo conf.d files (/etc/conf.d/). Creates all necessary dirs.

doenvd <env.d entry> [list of more env.d entries]
    Install Gentoo env.d entries. They will be installed into the correct location for Gentoo env.d entries (/etc/env.d/). Creates all necessary dirs.
dolib <library> [list of more libraries]
dolib.a <library> [list of more libraries]
dolib.so <library> [list of more libraries]
    Installs a library or a list of libraries into DESTTREE/lib. Creates all necessary dirs.

libopts [options for install(1)]
    Can be used to define options for the install function used in the dolib functions. The default is -m0644.

doman [-i18n=<locale>] <man-page> [list of more man-pages]
    Installs manual-pages into /usr/share/man/man[0-9n] depending on the manual file ending. The files are compressed if they are not already. You can specify locale-specific manpages with the -i18n option. Then the man-page will be installed into /usr/share/man/<locale>/man[0-9n].
dohard <filename> <linkname>
dosym <filename> <linkname>
    Performs the ln command as either a hard link or symlink.

dohtml  [-a filetypes] [-r] [-x list-of-dirs-to-ignore] [list-of-files-and-dirs]
    Installs the files in the list of files (space-separated list) into /usr/share/doc/${PF}/html provided the file ends in .html, .png, .js, .jpg, or .css. Setting -a limits what types of files will be included, -A appends to the default list, setting -x sets which dirs to exclude (CVS excluded by default), -r sets recursive.

doinfo <info-file> [list of more info-files]
    Installs info-pages into DESTDIR/info. Files are automatically gzipped. Creates all necessary dirs.

domo <locale-file> [list of more locale-files]
    Installs locale-files into DESTDIR/usr/share/locale/[LANG] depending on local-file's ending. Creates all necessary dirs.
fowners <permissions> <file> [files]
fperms <permissions> <file> [files]
    Performs chown (fowners) or chmod (fperms), applying permissions to files.

insinto [path]
    Sets the root (INSDESTTREE) for the doins function.
    The default root is /.

insopts [options for install(1)]
    Can be used to define options for the install function used in doins. The default is -m0644.

doins <file> [list of more files]
    Installs files into INSDESTTREE. This function uses install(1). Creates all necessary dirs.

exeinto [path]
    Sets the root (EXEDESTTREE) for the doexe function.
    The default root is /.

exeopts [options for install(1)]
    Can be used to define options for the install function used in doexe. The default is -m0755.

doexe <executable> [list of more executables]
    Installs a executable or a list of executable into EXEDESTTREE. This function uses install(1). Creates all necessary dirs.

docinto [path]
    Sets the relative subdir (DOCDESTTREE) used by dodoc.

dodoc <document> [list of more documents]
    Installs a document or a list of document into /usr/share/doc/${PF}/DOCDESTTREE. Files are automatically gzipped. Creates all necessary dirs.
newbin <old file> <new filename>
newsbin <old file> <new filename>
newinitd <old file> <new filename>
newconfd <old file> <new filename>
newenvd <old file> <new filename>
newlib <old file> <new filename>
newlib.so <old file> <new filename>
newlib.a <old file> <new filename>
newman <old file> <new filename>
newinfo <old file> <new filename>
newins <old file> <new filename>
newexe <old file> <new filename>
newdoc <old file> <new filename>
    All these functions act like the do* functions, but they only work with one file and the file is installed as [new filename].

REPORTING BUGS
Please report bugs via http://bugs.gentoo.org/

AUTHORS
Achim Gottinger <achim@gentoo.org>
Mark Guertin <gerk@gentoo.org>
Nicholas Jones <carpaski@gentoo.org>
Mike Frysinger <vapier@gentoo.org>
Arfrever Frehtes Taifersar Arahesis <FFTA@WP.PL>

FILES

The /usr/sbin/ebuild.sh script.

The helper apps in /usr/lib/portage/bin.

/etc/make.conf
    Contains variables for the build-process and overwrites those in make.defaults.

/etc/make.globals
    Contains the default variables for the build-process, you should edit /etc/make.conf instead.

SEE ALSO
ebuild(1), make.conf(5)