emacs: Text Coding
22.9 Specifying a Coding System for File Text
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In cases where Emacs does not automatically choose the right coding
system for a file’s contents, you can use these commands to specify one:
‘C-x <RET> f CODING <RET>’
Use coding system CODING to save or revisit the file in the current
buffer (‘set-buffer-file-coding-system’).
‘C-x <RET> c CODING <RET>’
Specify coding system CODING for the immediately following command
(‘universal-coding-system-argument’).
‘C-x <RET> r CODING <RET>’
Revisit the current file using the coding system CODING
(‘revert-buffer-with-coding-system’).
‘M-x recode-region <RET> RIGHT <RET> WRONG <RET>’
Convert a region that was decoded using coding system WRONG,
decoding it using coding system RIGHT instead.
The command ‘C-x <RET> f’ (‘set-buffer-file-coding-system’) sets the
file coding system for the current buffer (i.e., the coding system to
use when saving or reverting the file). You specify which coding system
using the minibuffer. You can also invoke this command by clicking with
‘mouse-3’ on the coding system indicator in the mode line (
Mode
Line).
If you specify a coding system that cannot handle all the characters
in the buffer, Emacs will warn you about the troublesome characters, and
ask you to choose another coding system, when you try to save the buffer
(Output Coding).
You can also use this command to specify the end-of-line conversion
(end-of-line conversion Coding Systems.) for encoding the current
buffer. For example, ‘C-x <RET> f dos <RET>’ will cause Emacs to save
the current buffer’s text with DOS-style carriage-return linefeed line
endings.
Another way to specify the coding system for a file is when you visit
the file. First use the command ‘C-x <RET> c’
(‘universal-coding-system-argument’); this command uses the minibuffer
to read a coding system name. After you exit the minibuffer, the
specified coding system is used for _the immediately following command_.
So if the immediately following command is ‘C-x C-f’, for example, it
reads the file using that coding system (and records the coding system
for when you later save the file). Or if the immediately following
command is ‘C-x C-w’, it writes the file using that coding system. When
you specify the coding system for saving in this way, instead of with
‘C-x <RET> f’, there is no warning if the buffer contains characters
that the coding system cannot handle.
Other file commands affected by a specified coding system include
‘C-x i’ and ‘C-x C-v’, as well as the other-window variants of ‘C-x
C-f’. ‘C-x <RET> c’ also affects commands that start subprocesses,
including ‘M-x shell’ (Shell). If the immediately following
command does not use the coding system, then ‘C-x <RET> c’ ultimately
has no effect.
An easy way to visit a file with no conversion is with the ‘M-x
find-file-literally’ command. Visiting.
The default value of the variable ‘buffer-file-coding-system’
specifies the choice of coding system to use when you create a new file.
It applies when you find a new file, and when you create a buffer and
then save it in a file. Selecting a language environment typically sets
this variable to a good choice of default coding system for that
language environment.
If you visit a file with a wrong coding system, you can correct this
with ‘C-x <RET> r’ (‘revert-buffer-with-coding-system’). This visits
the current file again, using a coding system you specify.
If a piece of text has already been inserted into a buffer using the
wrong coding system, you can redo the decoding of it using ‘M-x
recode-region’. This prompts you for the proper coding system, then for
the wrong coding system that was actually used, and does the conversion.
It first encodes the region using the wrong coding system, then decodes
it again using the proper coding system.
Info Catalog
emacs: Output Coding
emacs: International
emacs: Communication Coding