general-concepts/install-destinations/text.xml


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<?xml version="1.0"?>
<guide self="general-concepts/install-destinations/">
<chapter>
<title>Install Destinations</title>

<body>

<p>
When an ebuild runs the <c>src_install</c> phase, it installs an image of the
package in question from <c>${S}</c> into <c>${D}</c>. Ebuilds must <e>not</e> attempt to
perform any operation upon the live filesystem at this stage -- this will break
binaries, and will (often) cause a sandbox violation notice.
</p>

<p>
When installing, portage will install the image in <c>${D}</c> into <c>${ROOT}</c>. By
default, <c>${ROOT}</c> points to <c>/</c>, although the user can alter this -- for
example, the user may be building a minimal image for another system in a
different location. If your package must operate on the live filesystem (for
example, to create some cache files during <c>pkg_postinst</c>), you must ensure
that you prefix any paths with <c>${ROOT}</c>.
</p>

<p>
When inside <c>pkg_preinst</c>, the image to be installed can be accessed under
<c>"${IMAGE}"</c>.
</p>

</body>
</chapter>
</guide>