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(elisp)Specifying Coding Systems

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Specifying a Coding System for One Operation
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   You can specify the coding system for a specific operation by binding
the variables `coding-system-for-read' and/or `coding-system-for-write'.

 - Variable: coding-system-for-read
     If this variable is non-`nil', it specifies the coding system to
     use for reading a file, or for input from a synchronous subprocess.

     It also applies to any asynchronous subprocess or network stream,
     but in a different way: the value of `coding-system-for-read' when
     you start the subprocess or open the network stream specifies the
     input decoding method for that subprocess or network stream.  It
     remains in use for that subprocess or network stream unless and
     until overridden.

     The right way to use this variable is to bind it with `let' for a
     specific I/O operation.  Its global value is normally `nil', and
     you should not globally set it to any other value.  Here is an
     example of the right way to use the variable:

          ;; Read the file with no character code conversion.
          ;; Assume CRLF represents end-of-line.
          (let ((coding-system-for-write 'emacs-mule-dos))
            (insert-file-contents filename))

     When its value is non-`nil', `coding-system-for-read' takes
     precedence over all other methods of specifying a coding system to
     use for input, including `file-coding-system-alist',
     `process-coding-system-alist' and `network-coding-system-alist'.

 - Variable: coding-system-for-write
     This works much like `coding-system-for-read', except that it
     applies to output rather than input.  It affects writing to files,
     as well as sending output to subprocesses and net connections.

     When a single operation does both input and output, as do
     `call-process-region' and `start-process', both
     `coding-system-for-read' and `coding-system-for-write' affect it.

 - Variable: inhibit-eol-conversion
     When this variable is non-`nil', no end-of-line conversion is done,
     no matter which coding system is specified.  This applies to all
     the Emacs I/O and subprocess primitives, and to the explicit
     encoding and decoding functions (Note: Explicit Encoding).