patch-2.1.43 linux/Documentation/binfmt_misc.txt

• Lines: 84
• Date: Thu Jun 12 16:22:04 1997
• Orig file: v2.1.42/linux/Documentation/binfmt_misc.txt
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.42/linux/Documentation/binfmt_misc.txt linux/Documentation/binfmt_misc.txt
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+	Kernel Support for miscellaneous (your favourite) Binary Formats v1.1
+	====================================================================
+
+This Kernel feature allows to invoke almost (for restrictions see below) every
+program by simply typing it's name in the shell.
+This includes for example compiled Java(TM), Python or Emacs programs.
+
+To achieve this you must tell binfmt_misc which interpreter has to be invoked with
+which binary. Binfmt_misc recognises the binary-type by matching some bytes at the
+beginning of the file with a magic byte sequence (masking out specified bits) you
+have supplied. Binfmt_misc can also recognise a filename extension (aka .com) and
+optionally strip it off.
+
+To actually register a new binary type, you have to set up a string looking like
+:name:type:offset:magic:mask:interpreter: (where you can choose the ':' upon your
+needs) and echo it to /proc/sys/fs/binfmt_misc/register.
+Here is what the fields mean:
+ - 'name' is an identifier string. A new /proc file will be created with this
+   this name below /proc/sys/fs/binfmt_misc
+ - 'type' is the type of recognition. Give 'M' for magic and 'E' for extension.
+   Give the corresponding lowercase letter to let binfmt_misc strip of the
+   filename extension.
+ - 'offset' is the offset of the magic/mask in the file counted in bytes. This
+   defaults to 0 if you omit it (i.e. you write ':name:type::magic...')
+ - 'magic' is the byte sequence binfmt_misc is matching for. The magic string
+   may contain hex-encoded characters like \x0a or \xA4. In a shell environment
+   you will have to write \\x0a to prevent the shell from eating your \.
+   If you chose filename extension matching, this is the extension to be
+   recognised (the \x0a specials are not allowed). Extension matching is case
+   sensitive!
+ - 'mask' is an (optional, defaults to all 0xff) mask. You can mask out some bits
+   from matching by supplying a string like magic and as long as magic. The
+   mask is anded with the byte sequence of the file.
+ - 'interpreter' is the program that should be invoked with the binary as first
+   argument (specify the full path)
+There are some restrictions:
+ - the whole register string may not exceed 255 characters
+ - the magic must resist in the first 128 bytes of the file, i.e. offset+size(magic)
+   has to be less than 128
+ - the interpreter string may not exceed 127 characters
+You may want to add the binary formats in one of your /etc/rc scripts during boot-up.
+Read the manual of your init program to figure out how to do this right.
+
+
+A few examples (assumed you are in /proc/sys/fs/binfmt_misc):
+
+- enable Java(TM)-support (like binfmt_java):
+  echo ":Java:M::\xca\xfe\xba\xbe::/usr/local/bin/java:" > register
+  echo :Applet:M::\<\!--applet::/usr/local/bin/appletviewer: > register
+- enable support for em86 (like binfmt_em86, for Alpha AXP only):
+  echo ":i386:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x03:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:" > register
+  echo ":i486:M::\x7fELF\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x06:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfb\xff\xff:/bin/em86:" > register
+- enable support for packed DOS applications (pre-configured dosemu hdimages):
+  echo ":DEXE:M::\x0eDEX::/usr/bin/dosexec:" > register
+- enable support for DOS/Windows executables (using mzloader and dosemu/wine):
+  echo ":DOSWin:M::MZ::/usr/sbin/mzloader:" > register
+  echo ":DOS:E::com::/usr/sbin/mzloader:" > register
+
+
+You can enable/disable binfmt_misc or one binary type by echoing 0 (to disable)
+or 1 (to enable) to /proc/sys/fs/binfmt_misc/status or /proc/.../the_name.
+Catting the file tells you the current status of binfmt_misc/the entry.
+
+You can remove one entry or all entries by echoing -1 to /proc/.../the_name
+or /proc/sys/fs/binfmt_misc/status.
+
+
+HINTS:
+======
+
+If your interpreter does not look at the PATH to determine the full name of the
+program, you need to invoke a wrapper-script (like the following for java) first:
+
+#!/bin/sh
+FOO=`which $1` || exit 1
+shift
+/usr/local/bin/java $FOO ${1+$@}
+
+
+There is a web page about binfmt_misc at
+http://www.anatom.uni-tuebingen.de/~richi/linux/binfmt_misc.html
+
+Richard Günther, richard.guenther@student.uni-tuebingen.de