26.10 Contents of Directories

A directory is a kind of file that contains other files entered under various names. Directories are a feature of the file system.

Emacs can list the names of the files in a directory as a Lisp list, or display the names in a buffer using the ls shell command. In the latter case, it can optionally display information about each file, depending on the options passed to the ls command.

Function: directory-files directory &optional full-name match-regexp nosort count

This function returns a list of the names of the files in the directory directory. By default, the list is in alphabetical order.

If full-name is non-nil, the function returns the files’ absolute file names. Otherwise, it returns the names relative to the specified directory.

If match-regexp is non-nil, this function returns only those file names whose non-directory part contain a match for that regular expression—the other file names are excluded from the list. On case-insensitive filesystems, the regular expression matching is case-insensitive.

If nosort is non-nil, directory-files does not sort the list, so you get the file names in no particular order. Use this if you want the utmost possible speed and don’t care what order the files are processed in. If the order of processing is visible to the user, then the user will probably be happier if you do sort the names.

If count is non-nil, the function will return names of first count number of files, or names of all files, whichever occurs first. count has to be an integer greater than zero.

(directory-files "~lewis")
     ⇒ ("#foo#" "#foo.el#" "." ".."
         "dired-mods.el" "files.texi"

An error is signaled if directory is not the name of a directory that can be read.

Function: directory-empty-p directory

This utility function returns t if given directory is an accessible directory and it does not contain any files, i.e., is an empty directory. It will ignore ‘.’ and ‘..’ on systems that return them as files in a directory.

Symbolic links to directories count as directories. See file-symlink-p to distinguish symlinks.

Function: directory-files-recursively directory regexp &optional include-directories predicate follow-symlinks

Return all files under directory whose names match regexp. This function searches the specified directory and its sub-directories, recursively, for files whose basenames (i.e., without the leading directories) match the specified regexp, and returns a list of the absolute file names of the matching files (see absolute file names). The file names are returned in depth-first order, meaning that files in some sub-directory are returned before the files in its parent directory. In addition, matching files found in each subdirectory are sorted alphabetically by their basenames. By default, directories whose names match regexp are omitted from the list, but if the optional argument include-directories is non-nil, they are included.

By default, all subdirectories are descended into. If predicate is t, errors when trying to descend into a subdirectory (for instance, if it’s not readable by this user) are ignored. If it’s neither nil nor t, it should be a function that takes one parameter (the subdirectory name) and should return non-nil if the directory is to be descended into.

Symbolic links to subdirectories are not followed by default, but if follow-symlinks is non-nil, they are followed.

Function: locate-dominating-file file name

Starting at file, go up the directory tree hierarchy looking for the first directory where name, a string, exists, and return that directory. If file is a file, its directory will serve as the starting point for the search; otherwise file should be a directory from which to start. The function looks in the starting directory, then in its parent, then in its parent’s parent, etc., until it either finds a directory with name or reaches the root directory of the filesystem without finding name – in the latter case the function returns nil.

The argument name can also be a predicate function. The predicate is called for every directory examined by the function, starting from file (even if file is not a directory). It is called with one argument (the file or directory) and should return non-nil if that directory is the one it is looking for.

Function: file-in-directory-p file dir

This function returns t if file is a file in directory dir, or in a subdirectory of dir. It also returns t if file and dir are the same directory. It compares the truenames of the two directories. If dir does not name an existing directory, the return value is nil.

Function: directory-files-and-attributes directory &optional full-name match-regexp nosort id-format count

This is similar to directory-files in deciding which files to report on and how to report their names. However, instead of returning a list of file names, it returns for each file a list (filename . attributes), where attributes is what file-attributes returns for that file. The optional argument id-format has the same meaning as the corresponding argument to file-attributes (see Definition of file-attributes).

Constant: directory-files-no-dot-files-regexp

This regular expression matches any file name except ‘.’ and ‘..’. More precisely, it matches parts of any nonempty string except those two. It is useful as the match-regexp argument to directory-files and directory-files-and-attributes:

(directory-files "/foo" nil directory-files-no-dot-files-regexp)

returns nil, if directory ‘/foo’ is empty.

Function: file-expand-wildcards pattern &optional full regexp

This function expands the wildcard pattern pattern, returning a list of file names that match it.

pattern is, by default, a “glob”/wildcard string, e.g., ‘"/tmp/*.png"’ or ‘"/*/*/foo.png"’, but can also be a regular expression if the optional regexp parameter is non-nil. In any case, the matches are applied per sub-directory, so a match can’t span a parent/sub directory.

If pattern is written as an absolute file name, the values are absolute also.

If pattern is written as a relative file name, it is interpreted relative to the current default directory. The file names returned are normally also relative to the current default directory. However, if full is non-nil, they are absolute.

Function: insert-directory file switches &optional wildcard full-directory-p

This function inserts (in the current buffer) a directory listing for directory file, formatted with ls according to switches. It leaves point after the inserted text. switches may be a string of options, or a list of strings representing individual options.

The argument file may be either a directory or a file specification including wildcard characters. If wildcard is non-nil, that means treat file as a file specification with wildcards.

If full-directory-p is non-nil, that means the directory listing is expected to show the full contents of a directory. You should specify t when file is a directory and switches do not contain ‘-d’. (The ‘-d’ option to ls says to describe a directory itself as a file, rather than showing its contents.)

On most systems, this function works by running a directory listing program whose name is in the variable insert-directory-program. If wildcard is non-nil, it also runs the shell specified by shell-file-name, to expand the wildcards.

MS-DOS and MS-Windows systems usually lack the standard Unix program ls, so this function emulates the standard Unix program ls with Lisp code.

As a technical detail, when switches contains the long ‘--dired’ option, insert-directory treats it specially, for the sake of dired. However, the normally equivalent short ‘-D’ option is just passed on to insert-directory-program, as any other option.

Variable: insert-directory-program

This variable’s value is the program to run to generate a directory listing for the function insert-directory. It is ignored on systems which generate the listing with Lisp code.