binfmt_misc

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binfmt_misc is a capability of the Linux kernel which allows arbitrary executable file formats to be recognized and passed to certain user space applications, such as emulators and virtual machines.

The executable formats are registered through a special purpose file system interface (similar to /proc). Debian-based distributions provide the functionality through an extra binfmt-support package.[1]

Registration[edit]

The register file contains lines which define executable types to be handled. Each line is of the form:

:name:type:offset:magic:mask:interpreter:

  • name is the name of the binary format.
  • type is either E or M
    • If it is E, the executable file format is identified by its filename extension: magic is the file extension to be associated with the binary format; offset and mask are ignored.
    • If it is M, the format is identified by magic number at an absolute offset in the file and mask is a bitmask indicating which bits in the number are significant.
  • interpreter is a program that is to be run with the matching file as an argument.

Each format has a corresponding file entry in the /proc/sys/fs/binfmt_misc directory which can be read to get information about a given file format.

Common usage[edit]

binfmt_misc allows Java programs to be passed directly to the Java virtual machine.[2]

Another common usage is to execute PE executables (compiled for MS-DOS or Microsoft Windows) through Wine. For example, the following line will run DOS and Windows EXE files (identified by the "MZ" type code) using Wine:

:DOSWin:M::MZ::/usr/bin/wine:

To run EXE (.NET) files with Mono:[3][4]

:CLR:M::MZ::/usr/bin/mono:

See also[edit]

References[edit]

External links[edit]