@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001,
-@c 2002, 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+@c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+@c Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../../info/files
@node Files, Backups and Auto-Saving, Documentation, Top
* Changing Files:: Renaming files, changing protection, etc.
* File Names:: Decomposing and expanding file names.
* Contents of Directories:: Getting a list of the files in a directory.
-* Create/Delete Dirs:: Creating and Deleting Directories.
-* Magic File Names:: Defining "magic" special handling
- for certain file names.
+* Create/Delete Dirs:: Creating and Deleting Directories.
+* Magic File Names:: Defining "magic" special handling
+ for certain file names.
* Format Conversion:: Conversion to and from various file formats.
@end menu
and never treat wildcard characters specially.
@end defopt
-@defvar find-file-hook
+@defopt find-file-hook
The value of this variable is a list of functions to be called after a
file is visited. The file's local-variables specification (if any) will
have been processed before the hooks are run. The buffer visiting the
file is current when the hook functions are run.
This variable is a normal hook. @xref{Hooks}.
-@end defvar
+@end defopt
@defvar find-file-not-found-functions
The value of this variable is a list of functions to be called when
Normally, one of the functions in the
@code{after-insert-file-functions} list determines the coding system
(@pxref{Coding Systems}) used for decoding the file's contents,
-including end-of-line conversion.
+including end-of-line conversion. However, if the file contains null
+bytes, it is by default visited without any code conversions; see
+@ref{Lisp and Coding Systems, inhibit-null-byte-detection}, for how to
+control this behavior.
If @var{visit} is non-@code{nil}, this function additionally marks the
buffer as unmodified and sets up various fields in the buffer so that it
@menu
* Testing Accessibility:: Is a given file readable? Writable?
* Kinds of Files:: Is it a directory? A symbolic link?
-* Truenames:: Eliminating symbolic links from a file name.
+* Truenames:: Eliminating symbolic links from a file name.
* File Attributes:: How large is it? Any other names? Etc.
* Locating Files:: How to find a file in standard places.
@end menu
The time of last access, as a list of two integers.
The first integer has the high-order 16 bits of time,
the second has the low 16 bits. (This is similar to the
-value of @code{current-time}; see @ref{Time of Day}.)
+value of @code{current-time}; see @ref{Time of Day}.) Note that on
+some FAT-based filesystems, only the date of last access is recorded,
+so this time will always hold the midnight of the day of last access.
+@cindex modification time of file
@item
The time of last modification as a list of two integers (as above).
-@cindex modification time of file
+This is the last time when the file's contents were modified.
@item
The time of last status change as a list of two integers (as above).
+This is the time of the last change to the file's access mode bits,
+its owner and group, and other information recorded in the filesystem
+for the file, beyond the file's contents.
@item
The size of the file in bytes. If the size is too large to fit in a
deleted and recreated; @code{nil} otherwise.
@item
-The file's inode number. If possible, this is an integer. If the inode
-number is too large to be represented as an integer in Emacs Lisp, then
-the value has the form @code{(@var{high} . @var{low})}, where @var{low}
-holds the low 16 bits.
+The file's inode number. If possible, this is an integer. If the
+inode number is too large to be represented as an integer in Emacs
+Lisp, but still fits into a 32-bit integer, then the value has the
+form @code{(@var{high} . @var{low})}, where @var{low} holds the low 16
+bits. If the inode is wider than 32 bits, the value is of the form
+@code{(@var{high} @var{middle} . @var{low})}, where @code{high} holds
+the high 24 bits, @var{middle} the next 24 bits, and @var{low} the low
+16 bits.
@item
-The file system number of the file system that the file is in.
-Depending on the magnitude of the value, this can be either an integer
-or a cons cell, in the same manner as the inode number. This element
-and the file's inode number together give enough information to
-distinguish any two files on the system---no two files can have the same
-values for both of these numbers.
+The filesystem number of the device that the file is on. Depending on
+the magnitude of the value, this can be either an integer or a cons
+cell, in the same manner as the inode number. This element and the
+file's inode number together give enough information to distinguish
+any two files on the system---no two files can have the same values
+for both of these numbers.
@end enumerate
For example, here are the file attributes for @file{files.texi}:
@group
(file-attributes "files.texi" 'string)
@result{} (nil 1 "lh" "users"
- (8489 20284)
- (8489 20284)
- (8489 20285)
- 14906 "-rw-rw-rw-"
- nil 129500 -32252)
+ (19145 42977)
+ (19141 59576)
+ (18340 17300)
+ 122295 "-rw-rw-rw-"
+ nil (5888 2 . 43978)
+ (15479 . 46724))
@end group
@end example
@item "users"
is in the group with name "users".
-@item (8489 20284)
-was last accessed on Aug 19 00:09.
+@item (19145 42977)
+was last accessed on Oct 5 2009, at 10:01:37.
-@item (8489 20284)
-was last modified on Aug 19 00:09.
+@item (19141 59576)
+last had its contents modified on Oct 2 2009, at 13:49:12.
-@item (8489 20285)
-last had its inode changed on Aug 19 00:09.
+@item (18340 17300)
+last had its status changed on Feb 2 2008, at 12:19:00.
-@item 14906
-is 14906 bytes long. (It may not contain 14906 characters, though,
-if some of the bytes belong to multibyte sequences.)
+@item 122295
+is 122295 bytes long. (It may not contain 122295 characters, though,
+if some of the bytes belong to multibyte sequences, and also if the
+end-of-line format is CR-LF.)
@item "-rw-rw-rw-"
has a mode of read and write access for the owner, group, and world.
@item nil
would retain the same @acronym{GID} if it were recreated.
-@item 129500
-has an inode number of 129500.
-@item -32252
-is on file system number -32252.
+@item (5888 2 . 43978)
+has an inode number of 6473924464520138.
+
+@item (15479 . 46724)
+is on the file-system device whose number is 1014478468.
@end table
@end defun
+@cindex MS-DOS and file modes
+@cindex file modes and MS-DOS
+ On MS-DOS, there is no such thing as an ``executable'' file mode bit.
+So Emacs considers a file executable if its name ends in one of the
+standard executable extensions, such as @file{.com}, @file{.bat},
+@file{.exe}, and some others. Files that begin with the Unix-standard
+@samp{#!} signature, such as shell and Perl scripts, are also considered
+as executable files. This is reflected in the values returned by
+@code{file-modes} and @code{file-attributes}. Directories are also
+reported with executable bit set, for compatibility with Unix.
+
@node Locating Files
@subsection How to Locate Files in Standard Places
@cindex locate file in path
@var{modes} into the equivalent numeric value. If the symbolic
specification is based on an existing file, that file's mode bits are
taken from the optional argument @var{base-modes}; if that argument is
-omitted or nil, it defaults to zero, i.e.@: no access rights at all.
+omitted or @code{nil}, it defaults to zero, i.e.@: no access rights at
+all.
@end defun
@defun set-file-times filename &optional time
(@pxref{Time of Day}).
@end defun
-@cindex MS-DOS and file modes
-@cindex file modes and MS-DOS
- On MS-DOS, there is no such thing as an ``executable'' file mode bit.
-So Emacs considers a file executable if its name ends in one of the
-standard executable extensions, such as @file{.com}, @file{.bat},
-@file{.exe}, and some others. Files that begin with the Unix-standard
-@samp{#!} signature, such as shell and Perl scripts, are also considered
-as executable files. This is reflected in the values returned by
-@code{file-modes} and @code{file-attributes}. Directories are also
-reported with executable bit set, for compatibility with Unix.
-
@node File Names
@section File Names
@cindex file names
not an extension.
@end defun
-@ignore
-Andrew Innes says that this
-
-@c @defvar directory-sep-char
-This variable holds the character that Emacs normally uses to separate
-file name components. The default value is @code{?/}, but on MS-Windows
-you can set it to @code{?\\}; then the functions that transform file names
-use backslashes in their output.
-
-File names using backslashes work as input to Lisp primitives even on
-MS-DOS and MS-Windows, even if @code{directory-sep-char} has its default
-value of @code{?/}.
-@end defvar
-@end ignore
@node Relative File Names
@subsection Absolute and Relative File Names
name as an abbreviation for the ``real'' name, Emacs shows users the
abbreviation instead.
-@defvar directory-abbrev-alist
+@defopt directory-abbrev-alist
The variable @code{directory-abbrev-alist} contains an alist of
abbreviations to use for file directories. Each element has the form
@code{(@var{from} . @var{to})}, and says to replace @var{from} with
@var{to} when it appears in a directory name. The @var{from} string is
-actually a regular expression; it should always start with @samp{^}.
+actually a regular expression; it ought to always start with @samp{\`}.
The @var{to} string should be an ordinary absolute directory name. Do
not use @samp{~} to stand for a home directory in that string. The
function @code{abbreviate-file-name} performs these substitutions.
and so on.
@example
-(("^/home/fsf" . "/fsf")
- ("^/home/gp" . "/gp")
- ("^/home/gd" . "/gd"))
+(("\\`/home/fsf" . "/fsf")
+ ("\\`/home/gp" . "/gp")
+ ("\\`/home/gd" . "/gd"))
@end example
-@end defvar
+@end defopt
To convert a directory name to its abbreviation, use this
function:
@defun abbreviate-file-name filename
@anchor{Definition of abbreviate-file-name}
This function applies abbreviations from @code{directory-abbrev-alist}
-to its argument, and substitutes @samp{~} for the user's home
-directory. You can use it for directory names and for file names,
-because it recognizes abbreviations even as part of the name.
+to its argument, and also substitutes @samp{~} for the user's home
+directory if the argument names a file in the home directory or one of
+its subdirectories. (If the home directory is a root directory, it is
+not replaced with @samp{~}, because this does not make the result
+shorter on many systems.) You can use it for directory names and for
+file names, because it recognizes abbreviations even as part of the
+name.
@end defun
@node File Name Expansion
truncate the @var{string} prefix to fit into the 8+3 file-name limits.
@end defun
-@defvar temporary-file-directory
+@defopt temporary-file-directory
@cindex @code{TMPDIR} environment variable
@cindex @code{TMP} environment variable
@cindex @code{TEMP} environment variable
put the file in. However, if you expect the file to be small, you
should use @code{small-temporary-file-directory} first if that is
non-@code{nil}.
-@end defvar
+@end defopt
-@defvar small-temporary-file-directory
+@defopt small-temporary-file-directory
This variable specifies the directory name for
creating certain temporary files, which are likely to be small.
(or small-temporary-file-directory
temporary-file-directory)))
@end example
-@end defvar
+@end defopt
@node File Name Completion
@subsection File Name Completion
@end defvar
@node Create/Delete Dirs
-@section Creating and Deleting Directories
-@cindex creating and deleting directories
+@section Creating, Copying and Deleting Directories
+@cindex creating, copying and deleting directories
@c Emacs 19 features
Most Emacs Lisp file-manipulation functions get errors when used on
with @code{delete-file}. These special functions exist to create and
delete directories.
-@defun make-directory dirname &optional parents
-This function creates a directory named @var{dirname}.
-If @var{parents} is non-@code{nil}, as is always the case in an
+@findex mkdir
+@deffn Command make-directory dirname &optional parents
+This command creates a directory named @var{dirname}. If
+@var{parents} is non-@code{nil}, as is always the case in an
interactive call, that means to create the parent directories first,
if they don't already exist.
-@end defun
-@defun delete-directory dirname
-This function deletes the directory named @var{dirname}. The function
+@code{mkdir} is an alias for this.
+@end deffn
+
+@deffn Command copy-directory dirname newname &optional keep-time parents
+This command copies the directory named @var{dirname} to
+@var{newname}. If @var{newname} names an existing directory,
+@var{dirname} will be copied to a subdirectory there.
+
+It always sets the file modes of the copied files to match the
+corresponding original file.
+
+The third arg @var{keep-time} non-@code{nil} means to preserve the
+modification time of the copied files. A prefix arg makes
+@var{keep-time} non-@code{nil}.
+
+Noninteractively, the last argument @var{parents} says whether to
+create parent directories if they don't exist. Interactively,
+this happens by default.
+@end deffn
+
+@deffn Command delete-directory dirname &optional recursive
+This command deletes the directory named @var{dirname}. The function
@code{delete-file} does not work for files that are directories; you
-must use @code{delete-directory} for them. If the directory contains
-any files, @code{delete-directory} signals an error.
+must use @code{delete-directory} for them. If @var{recursive} is
+@code{nil}, and the directory contains any files,
+@code{delete-directory} signals an error.
-This function only follows symbolic links at the level of parent
-directories.
-@end defun
+@code{delete-directory} only follows symbolic links at the level of
+parent directories.
+@end deffn
@node Magic File Names
@section Making Certain File Names ``Magic''
regular expression), plus a handler that implements all the primitive
Emacs file operations for file names that do match.
+@vindex file-name-handler-alist
The variable @code{file-name-handler-alist} holds a list of handlers,
together with regular expressions that determine when to apply each
handler. Each element has this form:
@noindent
@code{access-file}, @code{add-name-to-file},
@code{byte-compiler-base-file-name},@*
-@code{copy-file}, @code{delete-directory},
-@code{delete-file},
+@code{copy-directory}, @code{copy-file},
+@code{delete-directory}, @code{delete-file},
@code{diff-latest-backup-file},
@code{directory-file-name},
@code{directory-files},
@flushleft
@code{access-file}, @code{add-name-to-file},
@code{byte-com@discretionary{}{}{}piler-base-file-name},
-@code{copy-file}, @code{delete-directory},
-@code{delete-file},
+@code{copy-directory}, @code{copy-file},
+@code{delete-directory}, @code{delete-file},
@code{diff-latest-backup-file},
@code{directory-file-name},
@code{directory-files},
@end defun
@defun unhandled-file-name-directory filename
-This function returns the name of a directory that is not magic.
-It uses the directory part of @var{filename} if that is not magic.
-For a magic file name, it invokes the file name handler, which
-therefore decides what value to return. If @var{filename} is not
-accessible from a local process, then the file name handler should
-indicate it by returning nil.
+This function returns the name of a directory that is not magic. It
+uses the directory part of @var{filename} if that is not magic. For a
+magic file name, it invokes the file name handler, which therefore
+decides what value to return. If @var{filename} is not accessible
+from a local process, then the file name handler should indicate it by
+returning @code{nil}.
This is useful for running a subprocess; every subprocess must have a
non-magic directory to serve as its current directory, and this function
is a good way to come up with one.
@end defun
+@defopt remote-file-name-inhibit-cache
+Whether to use the remote file-name cache for read access.
+
+File attributes of remote files are cached for better performance. If
+they are changed out of Emacs' control, the cached values become
+invalid, and must be reread.
+
+When set to @code{nil}, cached values are always used. This shall be
+set with care. When set to @code{t}, cached values are never used.
+ALthough this is the safest value, it could result in performance
+degradation.
+
+A compromise is to set it to a positive number. This means that
+cached values are used for that amount of seconds since they were
+cached.
+
+In case a remote file is checked regularly, it might be reasonable to
+let-bind this variable to a value less then the time period between
+two checks. Example:
+
+@example
+(defun display-time-file-nonempty-p (file)
+ (let ((remote-file-name-inhibit-cache (- display-time-interval 5)))
+ (and (file-exists-p file)
+ (< 0 (nth 7 (file-attributes (file-chase-links file)))))))
+@end example
+@end defopt
+
@node Format Conversion
@section File Format Conversion
and @code{write-region} for writing a buffer into a file.
@menu
-* Overview: Format Conversion Overview. @code{insert-file-contents} and @code{write-region}
+* Overview: Format Conversion Overview. @code{insert-file-contents} and @code{write-region}.
* Round-Trip: Format Conversion Round-Trip. Using @code{format-alist}.
* Piecemeal: Format Conversion Piecemeal. Specifying non-paired conversion.
@end menu
Each format definition is a list of this form:
@example
-(@var{name} @var{doc-string} @var{regexp} @var{from-fn} @var{to-fn} @var{modify} @var{mode-fn})
+(@var{name} @var{doc-string} @var{regexp} @var{from-fn} @var{to-fn} @var{modify} @var{mode-fn} @var{preserve})
@end example
@end defvar
@item regexp
A regular expression which is used to recognize files represented in
-this format.
+this format. If @code{nil}, the format is never applied automatically.
@item from-fn
A shell command or function to decode data in this format (to convert
A minor-mode function to call after visiting a file converted from this
format. The function is called with one argument, the integer 1;
that tells a minor-mode function to enable the mode.
+
+@item preserve
+A flag, @code{t} if @code{format-write-file} should not remove this format
+from @code{buffer-file-format}.
@end table
The function @code{insert-file-contents} automatically recognizes file
in the order of appearance in the list.
@deffn Command format-write-file file format &optional confirm
-This command writes the current buffer contents into the file
-@var{file} in format @var{format}, and makes that format the default
-for future saves of the buffer. The argument @var{format} is a list
-of format names. Except for the @var{format} argument, this command
-is similar to @code{write-file}. In particular, @var{confirm} has the
-same meaning and interactive treatment as the corresponding argument
-to @code{write-file}. @xref{Definition of write-file}.
+This command writes the current buffer contents into the file @var{file}
+in a format based on @var{format}, which is a list of format names. It
+constructs the actual format starting from @var{format}, then appending
+any elements from the value of @code{buffer-file-format} with a non-nil
+@var{preserve} flag (see above), if they are not already present in
+@var{format}. It then updates @code{buffer-file-format} with this
+format, making it the default for future saves. Except for the
+@var{format} argument, this command is similar to @code{write-file}. In
+particular, @var{confirm} has the same meaning and interactive treatment
+as the corresponding argument to @code{write-file}. @xref{Definition of
+write-file}.
@end deffn
@deffn Command format-find-file file format
@c ??? for `write-region-annotate-functions', below? --ttn
In contrast, when reading, the annotations intermixed with the text
-are handled immediately. @code{insert-file-contents} sets point to the
-beginning of some text to be converted, then calls the conversion
+are handled immediately. @code{insert-file-contents} sets point to
+the beginning of some text to be converted, then calls the conversion
functions with the length of that text. These functions should always
-return with point at the beginning of the inserted text. This approach
-makes sense for reading because annotations removed by the first
-converter can't be mistakenly processed by a later converter.
-
- Each conversion function should scan for the annotations it
-recognizes, remove the annotation, modify the buffer text (to set a text
-property, for example), and return the updated length of the text, as it
-stands after those changes. The value returned by one function becomes
-the argument to the next function.
+return with point at the beginning of the inserted text. This
+approach makes sense for reading because annotations removed by the
+first converter can't be mistakenly processed by a later converter.
+Each conversion function should scan for the annotations it
+recognizes, remove the annotation, modify the buffer text (to set a
+text property, for example), and return the updated length of the
+text, as it stands after those changes. The value returned by one
+function becomes the argument to the next function.
@defvar write-region-annotate-functions
A list of functions for @code{write-region} to call. Each function in
to be written. These functions should not alter the contents of the
buffer. Instead, they should return annotations.
-@c ??? Following adapted from comment in `build_annotations' (fileio.c).
-@c ??? Perhaps this is intended for internal use only?
-@c ??? Someone who understands this, please reword it. --ttn
-As a special case, if a function returns with a different buffer
-current, Emacs takes it to mean the current buffer contains altered text
-to be output, and discards all previous annotations because they should
-have been dealt with by this function.
+As a special case, a function may return with a different buffer
+current. Emacs takes this to mean that the current buffer contains
+altered text to be output. It therefore changes the @var{start} and
+@var{end} arguments of the @code{write-region} call, giving them the
+values of @code{point-min} and @code{point-max} in the new buffer,
+respectively. It also discards all previous annotations, because they
+should have been dealt with by this function.
+@end defvar
+
+@defvar write-region-post-annotation-function
+The value of this variable, if non-@code{nil}, should be a function.
+This function is called, with no arguments, after @code{write-region}
+has completed.
+
+If any function in @code{write-region-annotate-functions} returns with
+a different buffer current, Emacs calls
+@code{write-region-post-annotation-function} more than once. Emacs
+calls it with the last buffer that was current, and again with the
+buffer before that, and so on back to the original buffer.
+
+Thus, a function in @code{write-region-annotate-functions} can create
+a buffer, give this variable the local value of @code{kill-buffer} in
+that buffer, set up the buffer with altered text, and make the buffer
+current. The buffer will be killed after @code{write-region} is done.
@end defvar
@defvar after-insert-file-functions
HCoop / bpt / emacs.git / blobdiff