Apache Guide: Generating Fancy Directory Listings with mod_autoindex

Monday Oct 9th 2000 by Rich Bowen
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Sometimes you want to give users a wider selection of files to load. If you want to spiff up the default file listings that Apache returns when an index file is unavailable, you can generate fancy directory listings. Rich Bowen explains how.

When a user requests a directory without specifying a particular file name, Apache attempts to serve up a default document. The document served is determined by the directive DirectoryIndex, and is usually called index.html. However, if that document is not present, it is sometimes desirable to instead give a complete directory listing, permitting the user to select a file.

Directory listings are generated by the module mod_autoindex, which is compiled into Apache by default. Left to itself, it generates an uninteresting file listing, but with the techniques I'll show you in this article, you'll be able to make these listings as fancy as you like.

If your directory does not have a index.html in it, they you will get a directory listing, ordered by date, in which each filename is linked to that file for download. For each file, you are also given the last modified date of the file, and the size of the file.

There are a variety of default icons defined, so that different file types have different icons associated with them. And there's a link to the parent directory.

It's actually pretty nice, but there are some annoying things about it. The directories are interspersed amoung the files, rather than appearing at the top like most of us are used to. There's a Description column, but there's nothing actually in that column. And although files are alphabetically listed, the a's come after the Z's, rather than with the A's.

Some of the problems can be solved with the directives available in mod_autoindex.

For the whole story ...

For the full scoop on what you can do with mod_autoindex, you should see the documentation at http://www.apache.org/docs/mod/mod_autoindex.html I'm working on that while I work on this, so it should be a little more current by the time you read this.

Changing the Icons

To the left of each file name in a file listing, there's a little icon which presumably represents the type of file you're looking at. There's a pretty good selection of image files to choose from, but there are some file types missing, and occasionally you might want to have your own images, rather than the ones that ship with Apache.

There are three directives with which you can rectify this situation. These are the AddIcon, AddIconByType, and AddIconByEncoding. They let you specify a particular icon to be displayed, by file name, file type, or file encoding, respectively.

AddIcon lets you specify particular file names that should be displayed with a particular icon. The syntax of this directive is:


     AddIcon (ALT,/url/of/image.gif) filename

ALT is the alternate text to be displayed if the image does not load. filename can be a while file name, a wildcard, or some portion of a file name, such as a file extension. Examples might be:

     AddIcon (Image,/icons/image3.gif) .gif .jpg .png
     AddIcon /images/tmp.jpg *~

AddIconByType is the preferred directive, as it lets you specify an icon by mime type, rather than by file name. This allows for matching entire categories of files, rather than having to try to guess at file names.

     AddIconByType (Image,/icons/image1.gif) image/*

Finally, AddIconByEncoding lets you specify the icon by the mime encoding of the file. The syntax is the same as the other directives, and the argument is a mime-encoding:

     AddIconByEncoding /icons/compressed.gif x-compress

IndexOptions

The IndexOptions directive provides a list of options to set various features of the index listing. These options don't warrant their own directive, and so are lumped together here.

The syntax of the IndexOptions directive is:

     IndexOptions +option1 -option2 ...

Options marked with + will be included in the set of options, and those marked with - will be ommitted. Note that if you forget the + or - in that list, the last item on the list is all that you get. That is,

     IndexOptions SuppressDescription ScanHTMLTitles

is exactly the same directive as

     IndexOptions ScanHTMLTitles

And, furthermore, it overrides all previous IndexOptions directives that are already active. Don't forget the + and -!

I'm not going to go over all of the available options - see the docs - but here are a few that I like.

List Folders First

Those of you that are used to a graphical representation of your directories -- something like the Windows file explorer, for example -- are used to seeing the directories at the top of the listing, and the files below that. The default Apache view is to have the directories listed in the same alphabetic ordering as the files.

To override this behavior, use the FoldersFirst option:


     IndexOptions +FancyIndexing +FoldersFirst

Note that the FancyIndexing option is necessary for several of the options to work, including this one.

Descriptions from HTML Titles

Using the ScanHTMLTitles option, you can get a description of each HTML file in a listing by looking in the <TITLE> tag of each file. If you have written good HTML, this will give a very good idea of what each file is, before the user downloads. Note that in order to do this, Apache will need to open each file and parse it looking for a title tag. This can take a long time, and use up a lot of system resources.

Describe your Files

An exceptionally useful feature of mod_autoindex is the ability to provide descriptions for your files, and have these descriptions appear in the directory listing. This is accomplished with the AddDescription directive. As with several of these directive, you can specify exact file names, or you can give wild-cards to indicate a group of files.

     AddDescription "My dog" /images/fido.jpg
     AddDescription "PNG images" *.png

If you are in the habit of using really long file descriptions, or if you are using the ScanHTMLTitles option above, you might find that the space allocated to you for displaying a description is insufficient. You can correct oft this with the DescriptionWidth option. This is an option for the IndexOptions directive. You can specify a particular width, or you can specify ''*'', indicating that the field should be wide enough to accomodate the largest description you have.

     IndexOptions +DescriptionWidth=42

Readme Files

OK, one more. It may be desirable to display some informative text at the top of a directory list. This may be information about the files in the directory, or it might be administrative information about the server. Or whatever. The HeaderName and ReadmeName directives allow you to indicate a file that will be put at the top or bottom (respectively) of the directory listing. The argument for this directive is a filename stub. That means that if you have:


     ReadmeName README

and you have a file in that directory called README.html, that file will be displayed as the readme file for that directory.

Another neat trick here is that you can use HeaderName in conjunction with IndexOptions +SuppressHTMLPreamble, putting HTML in the header file to specify background, fonts, style sheets, or whatever you use on the rest of your site, so that the directory listing does not have to look like it does not belong to the rest of your site.

Conclusion

In the cases where you have directory listings rather than actual HTML pages, mod_autoindex can make these listings look exactly as you want them to, without having to generate custom directory listing pages for each directory.

Thanks for your feedback on my articles, and thanks for reading. Please drop me a note at ApacheToday@rcbowen.com if you have questions, or suggestions of topics you'd like for me to cover in future columns.

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