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.
systemd 257.9 BINFMT.D(5)
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