@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, 2009 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
@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
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
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 defopt
@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
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},
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
HCoop / bpt / emacs.git / blobdiff