binfmt.d(5) — Linux manual page

BINFMT.D(5)                     binfmt.d                     BINFMT.D(5)

NAME

       binfmt.d - Configure additional binary formats for executables at
       boot

SYNOPSIS

           /etc/binfmt.d/*.conf
           /run/binfmt.d/*.conf
           /usr/local/lib/binfmt.d/*.conf
           /usr/lib/binfmt.d/*.conf

DESCRIPTION

       At boot, systemd-binfmt.service(8) reads configuration files from
       the above directories to register in the kernel additional binary
       formats for executables.

CONFIGURATION FORMAT

       Each file contains a list of binfmt_misc kernel binary format
       rules. Consult the kernel's Kernel Support for miscellaneous
       Binary Formats (binfmt_misc)[1] documentation file for more
       information on registration of additional binary formats and how
       to write rules.

       Empty lines and lines beginning with ";" and "#" are ignored.
       Note that this means you may not use those symbols as the
       delimiter in binary format rules.

CONFIGURATION DIRECTORIES AND PRECEDENCE

       Configuration files are read from directories in /etc/, /run/,
       /usr/local/lib/, and /usr/lib/, in order of precedence, as listed
       in the SYNOPSIS section above. Files must have the ".conf"
       extension. Files in /etc/ override files with the same name in
       /run/, /usr/local/lib/, and /usr/lib/. Files in /run/ override
       files with the same name under /usr/.

       All configuration files are sorted by their filename in
       lexicographic order, regardless of which of the directories they
       reside in. If multiple files specify the same option, the entry
       in the file with the lexicographically latest name will take
       precedence. Thus, the configuration in a certain file may either
       be replaced completely (by placing a file with the same name in a
       directory with higher priority), or individual settings might be
       changed (by specifying additional settings in a file with a
       different name that is ordered later).

       Packages should install their configuration files in /usr/lib/
       (distribution packages) or /usr/local/lib/ (local installs) [2].
       Files in /etc/ are reserved for the local administrator, who may
       use this logic to override the configuration files installed by
       vendor packages.

       It is recommended to prefix all filenames with a two-digit number
       and a dash to simplify the ordering. It is recommended to use the
       range 10-40 for configuration files in /usr/ and the range 60-90
       for configuration files in /etc/ and /run/, to make sure that
       local and transient configuration files will always take priority
       over configuration files shipped by the OS vendor.

       If the administrator wants to disable a configuration file
       supplied by the vendor, the recommended way is to place a symlink
       to /dev/null in the configuration directory in /etc/, with the
       same filename as the vendor configuration file. If the vendor
       configuration file is included in the initrd image, the image has
       to be regenerated.

EXAMPLE

       Example 1. /etc/binfmt.d/wine.conf example:

           # Start WINE on Windows executables
           :DOSWin:M::MZ::/usr/bin/wine:

SEE ALSO

       systemd(1), systemd-binfmt.service(8), systemd-delta(1), wine(8)

NOTES

        1. Kernel Support for miscellaneous Binary Formats (binfmt_misc)
           https://docs.kernel.org/admin-guide/binfmt-misc.html

        2. 💣💥🧨💥💥💣 Please note that those configuration files must
           be available at all times. If /usr/local/ is a separate
           partition, it may not be available during early boot, and
           must not be used for configuration.

COLOPHON

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
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       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-13.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 257~devel                                            BINFMT.D(5)

Pages that refer to this page: systemd.directives(7), systemd.index(7), systemd-binfmt.service(8)

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