@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999
-@c Free Software Foundation, Inc.
+@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
@deffn Command find-file filename &optional wildcards
This command selects a buffer visiting the file @var{filename},
-using an existing buffer if there is one, and otherwise creating a
+using an existing buffer if there is one, and otherwise creating a
new buffer and reading the file into it. It also returns that buffer.
The body of the @code{find-file} function is very simple and looks
Visiting}). That function sets the buffer major mode, parses local
variables, warns the user if there exists an auto-save file more recent
than the file just visited, and finishes by running the functions in
-@code{find-file-hooks}.
+@code{find-file-hook}.
If the optional argument @var{rawfile} is non-@code{nil}, then
@code{after-find-file} is not called, and the
-@code{find-file-not-found-hooks} are not run in case of failure. What's
+@code{find-file-not-found-functions} are not run in case of failure. What's
more, a non-@code{nil} @var{rawfile} value suppresses coding system
conversion (@pxref{Coding Systems}) and format conversion (@pxref{Format
Conversion}).
not treated specially.
@end defvar
-@defvar find-file-hooks
+@defvar 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
it would not be advisable. @xref{Hooks}.
@end defvar
-@defvar find-file-not-found-hooks
+@defvar find-file-not-found-functions
The value of this variable is a list of functions to be called when
@code{find-file} or @code{find-file-noselect} is passed a nonexistent
file name. @code{find-file-noselect} calls these functions as soon as
If @var{nomodes} is non-@code{nil}, that means don't alter the buffer's
major mode, don't process local variables specifications in the file,
-and don't run @code{find-file-hooks}. This feature is used by
+and don't run @code{find-file-hook}. This feature is used by
@code{revert-buffer} in some cases.
The last thing @code{after-find-file} does is call all the functions
-in the list @code{find-file-hooks}.
+in the list @code{find-file-hook}.
@end defun
@node Saving Buffers
conversion (@pxref{Format Conversion}), and may save text properties in
``annotations'' (@pxref{Saving Properties}).
-@defvar write-file-hooks
+@defvar write-file-functions
The value of this variable is a list of functions to be called before
writing out a buffer to its visited file. If one of them returns
non-@code{nil}, the file is considered already written and the rest of
the functions are not called, nor is the usual code for writing the file
executed.
-If a function in @code{write-file-hooks} returns non-@code{nil}, it
+If a function in @code{write-file-functions} returns non-@code{nil}, it
is responsible for making a backup file (if that is appropriate).
To do so, execute the following code:
@code{backup-buffer} and use that to set the mode bits of the file that
you write. This is what @code{save-buffer} normally does.
-The hook functions in @code{write-file-hooks} are also responsible for
+The hook functions in @code{write-file-functions} are also responsible for
encoding the data (if desired): they must choose a suitable coding
system (@pxref{Lisp and Coding Systems}), perform the encoding
(@pxref{Explicit Encoding}), and set @code{last-coding-system-used} to
the coding system that was used (@pxref{Encoding and I/O}).
-Do not make this variable buffer-local. To set up buffer-specific hook
-functions, use @code{write-contents-hooks} instead.
+If you set this hook locally in a buffer, it is assumed to be
+associated with the file or the way the contents of the buffer were
+obtained. Thus the variable is marked as a permanent local, so that
+changing the major mode does not alter a buffer-local value. On the
+other hand, calling @code{set-visited-file-name} will reset it.
+If this is not what you want, you might like to use
+@code{write-contents-functions} instead.
Even though this is not a normal hook, you can use @code{add-hook} and
@code{remove-hook} to manipulate the list. @xref{Hooks}.
@end defvar
@c Emacs 19 feature
-@defvar local-write-file-hooks
-This works just like @code{write-file-hooks}, but it is intended to be
-made buffer-local in particular buffers, and used for hooks that pertain
-to the file name or the way the buffer contents were obtained.
-
-The variable is marked as a permanent local, so that changing the major
-mode does not alter a buffer-local value. This is convenient for
-packages that read ``file'' contents in special ways, and set up hooks
-to save the data in a corresponding way.
-@end defvar
-
-@c Emacs 19 feature
-@defvar write-contents-hooks
-This works just like @code{write-file-hooks}, but it is intended for
+@defvar write-contents-functions
+This works just like @code{write-file-functions}, but it is intended for
hooks that pertain to the contents of the file, as opposed to hooks that
pertain to where the file came from. Such hooks are usually set up by
major modes, as buffer-local bindings for this variable.
This variable automatically becomes buffer-local whenever it is set;
-switching to a new major mode always resets this variable. When you use
-@code{add-hooks} to add an element to this hook, you should @emph{not}
-specify a non-@code{nil} @var{local} argument, since this variable is
-used @emph{only} buffer-locally.
+switching to a new major mode always resets this variable.
@end defvar
@c Emacs 19 feature
This function works like @code{insert-file-contents} except that it does
not do format decoding (@pxref{Format Conversion}), does not do
character code conversion (@pxref{Coding Systems}), does not run
-@code{find-file-hooks}, does not perform automatic uncompression, and so
+@code{find-file-hook}, does not perform automatic uncompression, and so
on.
@end defun
If @var{mustbenew} is non-@code{nil}, then @code{write-region} asks
for confirmation if @var{filename} names an existing file.
-Starting in Emacs 21, if @var{mustbenew} is the symbol @code{excl},
+Starting in Emacs 21, if @var{mustbenew} is the symbol @code{excl},
then @code{write-region} does not ask for confirmation, but instead
it signals an error @code{file-already-exists} if the file already
exists.
These functions test for permission to access a file in specific ways.
@defun file-exists-p filename
-This function returns @code{t} if a file named @var{filename} appears to
-exist. This does not mean you can necessarily read the file, only that
-you can find out its attributes. (On Unix and GNU/Linux, this is true
-if the file exists and you have execute permission on the containing
-directories, regardless of the protection of the file itself.)
+This function returns @code{t} if a file named @var{filename} appears
+to exist. This does not mean you can necessarily read the file, only
+that you can find out its attributes. (On Unix and GNU/Linux, this is
+true if the file exists and you have execute permission on the
+containing directories, regardless of the protection of the file
+itself.)
If the file does not exist, or if fascist access control policies
prevent you from finding the attributes of the file, this function
returns @code{nil}.
+
+Directories are files, so @code{file-exists-p} returns @code{t} when
+given a directory name. However, symbolic links are treated
+specially; @code{file-exists-p} returns @code{t} for a symbolic link
+name only if the target file exists.
@end defun
@defun file-readable-p filename
@defun file-symlink-p filename
@cindex file symbolic links
-If the file @var{filename} is a symbolic link, the @code{file-symlink-p}
-function returns the file name to which it is linked. This may be the
-name of a text file, a directory, or even another symbolic link, or it
-may be a nonexistent file name.
+If the file @var{filename} is a symbolic link, the
+@code{file-symlink-p} function returns the link target as a string.
+(Determining the file name that the link points to from the target is
+nontrivial.)
If the file @var{filename} is not a symbolic link (or there is no such file),
-@code{file-symlink-p} returns @code{nil}.
+@code{file-symlink-p} returns @code{nil}.
@example
@group
holds the low 16 bits.
@item
-The file system number of the file system that the file is in. This
-element and the file's inode number together give enough information to
+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.
@end enumerate
@example
@group
(file-attributes "files.texi")
- @result{} (nil 1 2235 75
- (8489 20284)
- (8489 20284)
+ @result{} (nil 1 2235 75
+ (8489 20284)
+ (8489 20284)
(8489 20285)
- 14906 "-rw-rw-rw-"
+ 14906 "-rw-rw-rw-"
nil 129500 -32252)
@end group
@end example
@deffn Command copy-file oldname newname &optional ok-if-exists time
This command copies the file @var{oldname} to @var{newname}. An
-error is signaled if @var{oldname} does not exist.
+error is signaled if @var{oldname} does not exist. If @var{newname}
+names a directory, it copies @var{oldname} into that directory,
+preserving its final name component.
If @var{time} is non-@code{nil}, then this function gives the new file
the same last-modified time that the old one has. (This works on only
some operating systems.) If setting the time gets an error,
@code{copy-file} signals a @code{file-date-error} error.
+This function copies the file modes, too.
+
In an interactive call, this function prompts for @var{filename} and
@var{newname} in the minibuffer; also, it requests confirmation if
@var{newname} already exists.
@c Emacs 19 feature
@defun set-default-file-modes mode
+@cindex umask
This function sets the default file protection for new files created by
Emacs and its subprocesses. Every file created with Emacs initially has
this protection, or a subset of it (@code{write-region} will not give a
@menu
* File Name Components:: The directory part of a file name, and the rest.
+* Relative File Names:: Some file names are relative to a current directory.
* Directory Names:: A directory's name as a directory
is different from its name as a file.
-* Relative File Names:: Some file names are relative to a current directory.
* File Name Expansion:: Converting relative file names to absolute ones.
* Unique File Names:: Generating names for temporary files.
* File Name Completion:: Finding the completions for a given file name.
found mostly in directory lists.
@defun file-name-directory filename
-This function returns the directory part of @var{filename} (or
-@code{nil} if @var{filename} does not include a directory part). On
-most systems, the function returns a string ending in a slash. On VMS,
-it returns a string ending in one of the three characters @samp{:},
+This function returns the directory part of @var{filename}, as a
+directory name (@pxref{Directory Names}), or @code{nil} if
+@var{filename} does not include a directory part.
+
+On GNU and Unix systems, a string returned by this function always
+ends in a slash. On MSDOS it can also end in a colon. On VMS, it
+returns a string ending in one of the three characters @samp{:},
@samp{]}, or @samp{>}.
@example
@result{} "foo"
@end group
@group
+(file-name-nondirectory "lewis/")
+ @result{} ""
+@end group
+@group
;; @r{The following example is accurate only on VMS.}
(file-name-nondirectory "[X]FOO.TMP")
@result{} "FOO.TMP"
@end example
@end defun
+@defun file-name-extension filename &optional period
+This function returns @var{filename}'s final ``extension,'' if any,
+after applying @code{file-name-sans-versions} to remove any
+version/backup part. It returns @code{nil} for extensionless file
+names such as @file{foo}. If @var{period} is non-@code{nil}, then the
+returned value includes the period that delimits the extension, and if
+@var{filename} has no extension, the value is @code{""}. If the last
+component of a file name begins with a @samp{.}, that @samp{.} doesn't
+count as the beginning of an extension, so, for example,
+@file{.emacs}'s ``extension'' is @code{nil}, not @samp{.emacs}.
+@end defun
+
@defun file-name-sans-versions filename &optional keep-backup-version
This function returns @var{filename} with any file version numbers,
backup version numbers, or trailing tildes discarded.
@defun file-name-sans-extension filename
This function returns @var{filename} minus its ``extension,'' if any.
The extension, in a file name, is the part that starts with the last
-@samp{.} in the last name component. For example,
+@samp{.} in the last name component, except if that @samp{.} is the
+first character of the file name's last component. For example,
@example
(file-name-sans-extension "foo.lose.c")
@result{} "foo.lose"
(file-name-sans-extension "big.hack/foo")
@result{} "big.hack/foo"
+(file-name-sans-extension "/my/home/.emacs")
+ @result{} "/my/home/.emacs"
+(file-name-sans-extension "/my/home/.emacs.el")
+ @result{} "/my/home/.emacs"
@end example
@end defun
@ignore
-Andrew Innes says that this
+Andrew Innes says that this
@c @defvar directory-sep-char
@c @tindex directory-sep-char
@end defvar
@end ignore
-@defun file-name-extension filename &optional period
-This function returns @var{filename}'s final ``extension,'' if any,
-after applying @code{file-name-sans-versions} to remove any
-version/backup part. If @var{period} is non-nil, then the returned
-value includes the period that delimits the extension, and if
-@var{filename} has no extension, the value is @code{""}.
+@node Relative File Names
+@subsection Absolute and Relative File Names
+@cindex absolute file name
+@cindex relative file name
+
+ All the directories in the file system form a tree starting at the
+root directory. A file name can specify all the directory names
+starting from the root of the tree; then it is called an @dfn{absolute}
+file name. Or it can specify the position of the file in the tree
+relative to a default directory; then it is called a @dfn{relative} file
+name. On Unix and GNU/Linux, an absolute file name starts with a slash
+or a tilde (@samp{~}), and a relative one does not. On MS-DOS and
+MS-Windows, an absolute file name starts with a slash or a backslash, or
+with a drive specification @samp{@var{x}:/}, where @var{x} is the
+@dfn{drive letter}. The rules on VMS are complicated.
+
+@defun file-name-absolute-p filename
+This function returns @code{t} if file @var{filename} is an absolute
+file name, @code{nil} otherwise. On VMS, this function understands both
+Unix syntax and VMS syntax.
+
+@example
+@group
+(file-name-absolute-p "~rms/foo")
+ @result{} t
+@end group
+@group
+(file-name-absolute-p "rms/foo")
+ @result{} nil
+@end group
+@group
+(file-name-absolute-p "/user/rms/foo")
+ @result{} t
+@end group
+@end example
@end defun
@node Directory Names
@cindex directory name
@cindex file name of directory
- A @dfn{directory name} is the name of a directory. A directory is a
-kind of file, and it has a file name, which is related to the directory
-name but not identical to it. (This is not quite the same as the usual
-Unix terminology.) These two different names for the same entity are
-related by a syntactic transformation. On most systems, this is simple:
-a directory name ends in a slash (or backslash), whereas the directory's
-name as a file lacks that slash. On VMS, the relationship is more
-complicated.
+ A @dfn{directory name} is the name of a directory. A directory is
+actually a kind of file, so it has a file name, which is related to
+the directory name but not identical to it. (This is not quite the
+same as the usual Unix terminology.) These two different names for
+the same entity are related by a syntactic transformation. On GNU and
+Unix systems, this is simple: a directory name ends in a slash (or
+backslash), whereas the directory's name as a file lacks that slash.
+On MSDOS and VMS, the relationship is more complicated.
The difference between a directory name and its name as a file is
subtle but crucial. When an Emacs variable or function argument is
described as being a directory name, a file name of a directory is not
-acceptable.
+acceptable. When @code{file-name-directory} returns a string, that is
+always a directory name.
The following two functions convert between directory names and file
names. They do nothing special with environment variable substitutions
@end example
@end defun
+ Given a directory name, you can combine it with a relative file name
+using @code{concat}:
+
+@example
+(concat @var{dirname} @var{relfile})
+@end example
+
+@noindent
+Be sure to verify that the file name is relative before doing that.
+If you use an absolute file name, the results could be syntactically
+invalid or refer to the wrong file.
+
+ If you want to use a directory file name in making such a
+combination, you must first convert it to a directory name using
+@code{file-name-as-directory}:
+
+@example
+(concat (file-name-as-directory @var{dirfile}) @var{relfile})
+@end example
+
+@noindent
+Don't try concatenating a slash by hand, as in
+
+@example
+;;; @r{Wrong!}
+(concat @var{dirfile} "/" @var{relfile})
+@end example
+
+@noindent
+because this is not portable. Always use
+@code{file-name-as-directory}.
+
@cindex directory name abbreviation
Directory name abbreviations are useful for directories that are
normally accessed through symbolic links. Sometimes the users recognize
To convert a directory name to its abbreviation, use this
function:
-@defun abbreviate-file-name dirname
+@defun abbreviate-file-name filename
This function applies abbreviations from @code{directory-abbrev-alist}
to its argument, and substitutes @samp{~} for the user's home
-directory.
-@end defun
-
-@node Relative File Names
-@subsection Absolute and Relative File Names
-@cindex absolute file name
-@cindex relative file name
-
- All the directories in the file system form a tree starting at the
-root directory. A file name can specify all the directory names
-starting from the root of the tree; then it is called an @dfn{absolute}
-file name. Or it can specify the position of the file in the tree
-relative to a default directory; then it is called a @dfn{relative} file
-name. On Unix and GNU/Linux, an absolute file name starts with a slash
-or a tilde (@samp{~}), and a relative one does not. On MS-DOS and
-MS-Windows, an absolute file name starts with a slash or a backslash, or
-with a drive specification @samp{@var{x}:/}, where @var{x} is the
-@dfn{drive letter}. The rules on VMS are complicated.
-
-@defun file-name-absolute-p filename
-This function returns @code{t} if file @var{filename} is an absolute
-file name, @code{nil} otherwise. On VMS, this function understands both
-Unix syntax and VMS syntax.
-
-@example
-@group
-(file-name-absolute-p "~rms/foo")
- @result{} t
-@end group
-@group
-(file-name-absolute-p "rms/foo")
- @result{} nil
-@end group
-@group
-(file-name-absolute-p "/user/rms/foo")
- @result{} t
-@end group
-@end example
+directory. 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
@defun substitute-in-file-name filename
This function replaces environment variables references in
-@var{filename} with the environment variable values. Following standard
-Unix shell syntax, @samp{$} is the prefix to substitute an environment
-variable value.
+@var{filename} with the environment variable values. Following
+standard Unix shell syntax, @samp{$} is the prefix to substitute an
+environment variable value. If the input contains @samp{$$}, that is
+converted to @samp{$}; this gives the user a way to ``quote'' a
+@samp{$}.
The environment variable name is the series of alphanumeric characters
(including underscores) that follow the @samp{$}. If the character following
the @samp{$} is a @samp{@{}, then the variable name is everything up to the
matching @samp{@}}.
+Calling @code{substitute-in-file-name} on output produced by
+@code{substitute-in-file-name} tends to give incorrect results. For
+instance, use of @samp{$$} to quote a single @samp{$} won't work
+properly, and @samp{$} in an environment variable's value could lead
+to repeated substitution. Therefore, programs that call this function
+and put the output where it will be passed to this function need to
+double all @samp{$} characters to prevent subsequent incorrect
+results.
+
@c Wordy to avoid overfull hbox. --rjc 15mar92
Here we assume that the environment variable @code{HOME}, which holds
the user's home directory name, has value @samp{/xcssun/users/rms}.
@example
@group
(file-name-all-completions "f" "")
- @result{} ("foo" "file~" "file.c.~2~"
+ @result{} ("foo" "file~" "file.c.~2~"
"file.c.~1~" "file.c")
@end group
@group
-(file-name-all-completions "fo" "")
+(file-name-all-completions "fo" "")
@result{} ("foo")
@end group
@end example
@result{} (".o" ".elc" "~" ".dvi")
@end group
@end example
+
+If an element of @code{completion-ignored-extensions} ends in a slash
+@samp{/}, it signals a directory. The elements which do @emph{not} end
+in a slash will never match a directory; thus, the above value will not
+filter out a directory named @file{foo.elc}.
@end defopt
@node Standard File Names
@group
(directory-files "~lewis")
@result{} ("#foo#" "#foo.el#" "." ".."
- "dired-mods.el" "files.texi"
+ "dired-mods.el" "files.texi"
"files.texi.~1~")
@end group
@end example
The @var{handler} then needs to figure out whether to handle
@var{filename} or @var{dirname}.
+If the specified file name matches more than one handler, the one
+whose match starts last in the file name gets precedence. This rule
+is chosen so that handlers for jobs such as uncompression are handled
+first, before handlers for jobs such as remote file access.
+
Here are the operations that a magic file name handler gets to handle:
@ifnottex
@noindent
-@code{add-name-to-file}, @code{copy-file}, @code{delete-directory},
+@code{access-file}, @code{add-name-to-file},
+@code{byte-compiler-base-file-name},@*
+@code{copy-file}, @code{delete-directory},
@code{delete-file},
@code{diff-latest-backup-file},
@code{directory-file-name},
@code{directory-files},
+@code{directory-files-and-attributes},
@code{dired-call-process},
-@code{dired-compress-file}, @code{dired-uncache},
+@code{dired-compress-file}, @code{dired-uncache},@*
@code{expand-file-name},
-@code{file-accessible-directory-p},@*
+@code{file-accessible-directory-p},
@code{file-attributes},
@code{file-directory-p},
-@code{file-executable-p}, @code{file-exists-p},@*
+@code{file-executable-p}, @code{file-exists-p},
@code{file-local-copy},
-@code{file-modes}, @code{file-name-all-completions},@*
+@code{file-modes}, @code{file-name-all-completions},
@code{file-name-as-directory},
@code{file-name-completion},
@code{file-name-directory},
@code{file-readable-p}, @code{file-regular-p}, @code{file-symlink-p},
@code{file-truename}, @code{file-writable-p},
@code{find-backup-file-name},
-@code{get-file-buffer},@*
+@code{find-file-noselect},@*
+@code{get-file-buffer},
@code{insert-directory},
-@code{insert-file-contents},
+@code{insert-file-contents},@*
@code{load}, @code{make-directory},
-@code{make-symbolic-link}, @code{rename-file}, @code{set-file-modes},
-@code{set-visited-file-modtime}, @code{shell-command},@*
+@code{make-directory-internal},
+@code{make-symbolic-link},@*
+@code{rename-file}, @code{set-file-modes},
+@code{set-visited-file-modtime}, @code{shell-command},
+@code{substitute-in-file-name},@*
@code{unhandled-file-name-directory},
@code{vc-registered},
@code{verify-visited-file-modtime},@*
@iftex
@noindent
@flushleft
-@code{add-name-to-file}, @code{copy-file}, @code{delete-directory},
+@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{diff-latest-backup-file},
@code{directory-file-name},
@code{directory-files},
+@code{directory-files-and-at@discretionary{}{}{}tributes},
@code{dired-call-process},
@code{dired-compress-file}, @code{dired-uncache},
@code{expand-file-name},
@code{file-readable-p}, @code{file-regular-p}, @code{file-symlink-p},
@code{file-truename}, @code{file-writable-p},
@code{find-backup-file-name},
+@code{find-file-noselect},
@code{get-file-buffer},
@code{insert-directory},
@code{insert-file-contents},
@code{load}, @code{make-direc@discretionary{}{}{}tory},
-@code{make-symbolic-link}, @code{rename-file}, @code{set-file-modes},
+@code{make-direc@discretionary{}{}{}tory-internal},
+@code{make-symbolic-link},
+@code{rename-file}, @code{set-file-modes},
@code{set-visited-file-modtime}, @code{shell-command},
+@code{substitute-in-file-name},
@code{unhandled-file-name-directory},
@code{vc-regis@discretionary{}{}{}tered},
@code{verify-visited-file-modtime},
@dots{}
;; @r{Handle any operation we don't know about.}
(t (let ((inhibit-file-name-handlers
- (cons 'my-file-handler
+ (cons 'my-file-handler
(and (eq inhibit-file-name-operation operation)
inhibit-file-name-handlers)))
(inhibit-file-name-operation operation))
multiple handlers, and for operations that have two file names that may
each have handlers.
+@kindex safe-magic (@r{property})
+Handlers that don't really do anything specal for actual access to the
+file---such as the ones that implement completion of host names for
+remote file names---should have a non-@code{nil} @code{safe-magic}
+property. For instance, Emacs normally ``protects'' directory names
+it finds in @code{PATH} from becoming magic, if they look like magic
+file names, by prefixing them with @samp{/:}. But if the handler that
+would be used for them has a non-@code{nil} @code{safe-magic}
+property, the @samp{/:} is not added.
+
@defvar inhibit-file-name-handlers
This variable holds a list of handlers whose use is presently inhibited
for a certain operation.