<?xml version="1.0"?>

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

<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

alphabetical order, regardless in which of the

directories they reside, to guarantee that a specific

configuration file takes precedence over another file

with an alphabetically later name.</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><refentrytitle>wine</refentrytitle><manvolnum>8</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>