Commit 1ca54e68 authored by Eli Zaretskii's avatar Eli Zaretskii
Browse files

(Text and Binary): Separate description of EOL

conversions from the issues related to binary files.
parent bb746ea6
......@@ -146,7 +146,7 @@ is for compatibility with the Unix version, where the box cursor is the
default. This default shape can be changed to a bar by specifying the
@code{cursor-type} parameter in the variable @code{default-frame-alist}
(@pxref{Creating Frames}). The MS-DOS terminal doesn't support a
vertical-bar cursor, so the bar cursor is horizontal, and the its
vertical-bar cursor, so the bar cursor is horizontal, and the
@code{@var{width}} parameter, if specified by the frame parameters,
actually determines its height. As an extension, the bar cursor
specification can include the starting scan line of the cursor as well
......@@ -290,48 +290,41 @@ carriage-return linefeed when writing files. The same mechanism that
handles conversion of international character codes does this conversion
also (@pxref{Coding Systems}).
@cindex cursor location, under MS-DOS
@cindex point location, under MS-DOS
@cindex cursor location, on MS-DOS
@cindex point location, on MS-DOS
One consequence of this special format-conversion of most files is
that character positions as reported by Emacs (@pxref{Position Info}) do
not agree with the file size information known to the operating system.
@vindex file-name-buffer-file-type-alist
Some kinds of files should not be converted, because their contents
are not really text. Therefore, Emacs on MS-DOS distinguishes certain
files as @dfn{binary files}, and reads and writes them verbatim. (This
distinction is not part of MS-DOS; it is made by Emacs only.) These
include executable programs, compressed archives, etc. Emacs uses the
file name to decide whether to treat a file as binary: the variable
@code{file-name-buffer-file-type-alist} defines the file-name patterns
that indicate binary files. Note that if a file name matches one of the
patterns for binary files in @code{file-name-buffer-file-type-alist},
Emacs uses the @code{no-conversion} coding system (@pxref{Coding
Systems}) which turns off @emph{all} coding-system conversions, not only
the EOL conversion.
In addition, if Emacs recognizes from a file's contents that it uses
newline rather than carriage-return linefeed as its line separator, it
does not perform conversion when reading or writing that file. Thus,
does not perform EOL conversion when reading or writing that file. Thus,
you can read and edit files from Unix or GNU systems on MS-DOS with no
special effort, and they will be left with their Unix-style EOLs.
@findex find-file-text
@findex find-file-binary
You can visit a file and specify whether to treat a file as text or
binary using the commands @code{find-file-text} and
@code{find-file-binary}. End-of-line conversion is part of the general
coding system conversion mechanism, so another way to control whether to
treat a file as text or binary is with the commands for specifying a
coding system (@pxref{Specify Coding}). For example,
@kbd{C-x @key{RET} c undecided-unix @key{RET} C-x C-f foobar.txt}
visits the file @file{foobar.txt} without converting the EOLs.
The mode line indicates whether end-of-line translation was used for
the current buffer. Normally a colon appears after the coding system
letter near the beginning of the mode line. If MS-DOS end-of-line
translation is in use for the buffer, this character changes to a
backslash.
the current buffer. If MS-DOS end-of-line translation is in use for the
buffer, a backslash @samp{\} is displayed after the coding system
mnemonic near the beginning of the mode line (@pxref{Mode Line}). If no
EOL translation was performed, the string @samp{(Unix)} is displayed
instead of the backslash, to alert you that the file's EOL format is not
the usual carriage-return linefeed.
@cindex DOS-to-Unix conversion of files
@pindex dos2unix
End-of-line conversion is part of the general coding system conversion
mechanism, so the way to control whether to treat a text file as
DOS-style or Unix-style is with the commands for specifying a coding
system (@pxref{Specify Coding}). For example, @kbd{C-x @key{RET} c unix
@key{RET} C-x C-f foobar.txt} visits the file @file{foobar.txt} without
converting the EOLs; if that file has carriage-return linefeed pairs at
the end of its lines, Emacs will display @samp{^M} at the end of each
line. Similarly, you can force Emacs to save a buffer with specific EOL
format with the @kbd{C-x @key{RET} f} command. For example, to save a
buffer with Unix EOL format, type @kbd{C-x @key{RET} f unix @key{RET}
C-x C-s}. Thus, visiting a file with DOS EOL conversion, then saving it
with Unix EOL format effectively converts the file to Unix text style,
like the popular program @code{dos2unix} does.
@cindex untranslated file system
@findex add-untranslated-filesystem
......@@ -369,6 +362,50 @@ the function @code{remove-untranslated-filesystem}. This function takes
one argument, which should be a string just like the one that was used
previously with @code{add-untranslated-filesystem}.
Designating a file system as untranslated does @strong{not} disable
code conversions as specified by the coding systems set up by your
language environment, it only affects the EOL conversions, by forcing
Emacs to create new files with Unix-style newline-only EOLs.
@vindex file-name-buffer-file-type-alist
@cindex binary files, on MS-DOS/MS-Windows
Some kinds of files should not be converted at all, because their
contents are not really text. Therefore, Emacs on MS-DOS distinguishes
certain files as @dfn{binary files}. (This distinction is not part of
MS-DOS; it is made by Emacs only.) Binary files include executable
programs, compressed archives, etc. Emacs uses the file name to decide
whether to treat a file as binary: the variable
@code{file-name-buffer-file-type-alist} defines the file-name patterns
that indicate binary files. If a file name matches one of the patterns
for binary files (those whose associations are of the type
@code{(@var{pattern} . t)}, Emacs reads and writes that file using the
@code{no-conversion} coding system (@pxref{Coding Systems}) which turns
off @emph{all} coding-system conversions, not only the EOL conversion.
@code{file-name-buffer-file-type-alist} also includes file-name patterns
for files which are known to be DOS-style text files with
carriage-return linefeed EOL format, such as @file{CONFIG.SYS}; Emacs
always writes those files with DOS-style EOLs.
If a file which belongs to an untranslated file system matches one of
the file-name patterns in @code{file-name-buffer-file-type-alist}, the
EOL conversion is determined by @code{file-name-buffer-file-type-alist}.
@findex find-file-text
@findex find-file-binary
You can visit a file and specify whether to treat it as text or binary
using the commands @code{find-file-text} and @code{find-file-binary}.
@code{find-file-text} specifies DOS EOL conversions, but leaves the
other coding conversions unspecified (Emacs determines the required
conversions via the usual defaults and coding-detection mechanisms). On
the other hand, @code{find-file-binary} turns off @emph{all}
coding-system conversions.
@findex find-file-literally@r{, and binary files}
The @code{find-file-text} and @code{find-file-binary} commands are
only available when Emacs runs on MS-DOS or MS-Windows. The command
@code{find-file-literally}, which is available on all platforms,
produces the same effect as @code{find-file-binary}.
@node MS-DOS Printing
@section Printing and MS-DOS
......
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