Default src_install

For EAPI < 4, the default src_install function is the following:

src_install()
{
    return
}

For EAPI ≥ 4, the default src_install function is the following:

src_install() {
	if [[ -f Makefile ]] || [[ -f GNUmakefile]] || [[ -f makefile ]] ; then
		emake DESTDIR="${D}" install
	fi

	if ! declare -p DOCS >/dev/null 2>&1 ; then
		local d
		for d in README* ChangeLog AUTHORS NEWS TODO CHANGES THANKS BUGS \
				FAQ CREDITS CHANGELOG ; do
			[[ -s "${d}" ]] && dodoc "${d}"
		done
	elif declare -p DOCS | grep -q "^declare -a " ; then
		dodoc "${DOCS[@]}"
	else
		dodoc ${DOCS}
	fi
}

Sample src_install

src_install() {
    emake DESTDIR="${D}" install || die "Install failed"
    dodoc README CHANGES || die
}

Easy Installs

Often, especially with autotools-powered packages, there is a Makefile install target which will honour the DESTDIR variable to tell it to install to a non-root location. If possible, this should be used:

    emake DESTDIR="${D}" install || die "Install failed"

Sometimes this will end up installing a few things into strange places. If and only if this is the case, the einstall function can be used:

    einstall || die "einstall failed"

It is usually necessary to include additional dodoc statements for the README, ChangeLog, etc in these cases.

Trivial Installs

For some packages with no Makefile that only install a small number of files, writing a manual install using cp is the easiest option. For example, to do a simple install of some (no compilation required) themes:

    dodir /usr/share/foo-styles/
    cp -R "${S}/" "${D}/" || die "Install failed!"

Or sometimes a combination of insinto and doins (plus related functions -- see Install Functions Reference) — the following is based upon the sys-fs/udev install:

src_install() {
    dobin udevinfo || die
    dobin udevtest || die
    into /
    dosbin udev || die
    dosbin udevd || die
    dosbin udevsend || die
    dosbin udevstart || die
    dosbin extras/scsi_id/scsi_id || die
    dosbin extras/volume_id/udev_volume_id || die

    exeinto /etc/udev/scripts
    doexe extras/ide-devfs.sh || die
    doexe extras/scsi-devfs.sh || die
    doexe extras/cdsymlinks.sh || die
    doexe extras/dvb.sh || die

    insinto /etc/udev
    newins "${FILESDIR}/udev.conf.post_050" udev.conf || die
    doins extras/cdsymlinks.conf || die

    # For devfs style layout
    insinto /etc/udev/rules.d/
    newins etc/udev/gentoo/udev.rules 50-udev.rules || die

    # scsi_id configuration
    insinto /etc
    doins extras/scsi_id/scsi_id.config || die

    # set up symlinks in /etc/hotplug.d/default
    dodir /etc/hotplug.d/default || die
    dosym ../../../sbin/udevsend /etc/hotplug.d/default/10-udev.hotplug || die

    # set up the /etc/dev.d directory tree
    dodir /etc/dev.d/default || die
    dodir /etc/dev.d/net || die
    exeinto /etc/dev.d/net
    doexe etc/dev.d/net/hotplug.dev || die

    doman *.8 || die
    doman extras/scsi_id/scsi_id.8 || die

    dodoc ChangeLog FAQ HOWTO-udev_for_dev README TODO || die
    dodoc docs/{overview,udev-OLS2003.pdf,udev_vs_devfs,RFC-dev.d,libsysfs.txt} || die
    dodoc docs/persistent_naming/* docs/writing_udev_rules/* || die

    newdoc extras/volume_id/README README_volume_id || die
}

This is, of course, considerably harder to handle than a simple Makefile driven install.

Other Installs

Sometimes, there will be a Makefile that does not honour DESTDIR and a non-trivial number of files to install. In these situations, it is best to patch the Makefile and contact upstream explaining the situation to them.