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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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  This file is part of systemd.

  Copyright 2011 Lennart Poettering

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<refentry id="binfmt.d" conditional='ENABLE_BINFMT'>

        <refentryinfo>
                <title>binfmt.d</title>
                <productname>systemd</productname>

                <authorgroup>
                        <author>
                                <contrib>Developer</contrib>
                                <firstname>Lennart</firstname>
                                <surname>Poettering</surname>
                                <email>lennart@poettering.net</email>
                        </author>
                </authorgroup>
        </refentryinfo>

        <refmeta>
                <refentrytitle>binfmt.d</refentrytitle>
                <manvolnum>5</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>binfmt.d</refname>
                <refpurpose>Configure additional binary formats for
                executables at boot</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <para><filename>/etc/binfmt.d/*.conf</filename></para>
                <para><filename>/run/binfmt.d/*.conf</filename></para>
                <para><filename>/usr/lib/binfmt.d/*.conf</filename></para>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para>At boot,
                <citerefentry><refentrytitle>systemd-binfmt.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                reads configuration files from the above directories
                to register in the kernel additional binary
                formats for executables.</para>
        </refsect1>

        <refsect1>
                <title>Configuration Format</title>

                <para>Each file contains a list of binfmt_misc kernel
                binary format rules. Consult <ulink
                url="https://www.kernel.org/doc/Documentation/binfmt_misc.txt">binfmt_misc.txt</ulink>
                for more information on registration of additional
                binary formats and how to write rules.</para>

                <para>Empty lines and lines beginning with ; and # are
                ignored. Note that this means you may not use ; and #
                as delimiter in binary format rules.</para>

                <para>Each configuration file shall be named in the
                style of <filename><replaceable>program</replaceable>.conf</filename>.
                Files in <filename>/etc/</filename> override files
                with the same name in <filename>/usr/lib/</filename>
                and <filename>/run/</filename>. Files in
                <filename>/run/</filename> override files with the
                same name in <filename>/usr/lib/</filename>. Packages
                should install their configuration files in
                <filename>/usr/lib/</filename>, files in
                <filename>/etc/</filename> are reserved for the local
                administrator, who may use this logic to override the
                configuration files installed from vendor
                packages. All files are sorted by their filename in
                lexicographic order, regardless of which of the
                directories they reside in. If multiple files specify
                the same binary type name, the entry in the file with
                the lexicographically latest name will be applied.</para>

                <para>If the administrator wants to disable a
                configuration file supplied by the vendor, the
                recommended way is to place a symlink to
                <filename>/dev/null</filename> in
                <filename>/etc/binfmt.d/</filename> bearing the
                same filename.</para>
        </refsect1>

        <refsect1>
                <title>Example</title>
                <example>
                        <title>/etc/binfmt.d/wine.conf example:</title>

                        <programlisting># Start WINE on Windows executables
:DOSWin:M::MZ::/usr/bin/wine:</programlisting>
                </example>
        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd-binfmt.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry project='die-net'><refentrytitle>wine</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>
