Understanding the web site file system:

index.html and why you should use it:

This again is where a number of newer webmasters become stumped. They upload all of their files and directories, and then want to access them with their browser, but forget to name their home page index.html. Here's what happens: they access their site as http://www.mydomain.com, and what they see is their entire file directory structure! Yikes!… It looks just like exploring the C drive on your computer! You don't want visitors seeing that, do you?

When you access your site by calling it as http://www.mydomain.com the web server looks for the "index.html" file as the default file to be sent to visitors, and thus this is why http://www.mydomain.com by itself will automatically display the home or welcoming page. It's because the server automatically looks for index.html whenever a domain or directory is called without a filename appended to it such as this, http://www.mydomain.com/filename.xyz

If it can't find index.html, it will simply list "your entire web directory" to everyone that accesses it, which can be a security risk. You should use an "index.html" file in any directory you create, including your "root" web directory. In general, it's always a good idea to use "index.html" as your main page in all sub-directories on your account. Forgetting to place an index.html in your root web, or any subdirectory of your web for that matter will effectively leave all of its contents viewable to the world.

However, it is possible to specify the default webpage that visitors see when visiting any of your directories (e.g. http://www.mydomain.com/fun , http://www.mydomain.com/contact , etc.). To do so, you need to create a file called ".htacess" in that directory. Then, just open up that file and add the line

DirectoryIndex filename.xyz

where filename.xyz is the name of the page you want to load by default when someone accesses that folder with a browser. (Note that the file name is case sensitive.) Make sure to save the changes you made to the file.

For example, say you have a page called "home.html" that you want to have load by default when someone goes to http://www.your_domain.com . Just create a new file called ".htaccess" in your /public_html folder and add the line

DirectoryIndex home.html

to it. Now, when someone goes to http://www.your_domain.com , your home.html page will load by default. As another example, say you have another page called silly.html that you would like to load by default when someone goes to your http://fun.your_domain.com subdomain. Just create a new file called ".htaccess" in your /public_html/fun folder and add the line

DirectoryIndex silly.html

to it. Now, when someone goes to view http://fun.your_domain.com (or http://www.fun.your_domain.com, they're the same thing) in their browser, your silly.html page will load by default.
 

Understanding case sensitivity:

Another small detail, which can throw many newer users into a tailspin. Unlike your local PC, the Unix file system is very particular about "uppercase" and "lowercase" file names. Therefore, if you were to install a script, (let's say the wwwboard discussion forum) for example), the name of this script would be wwwboard.pl.  If you name a file picture file called me.jpg, then this is what you must call it as.  Naming it me.JPG for example, (observe the uppercase) tells a Unix web server to treat it as a totally different file name.

Unix file servers are exceptionally fussy on this issue, so make sure you pay close attention to case when uploading files, or installing and configuring cgi based scripts. The same rule applies for all files including your .html pages. Again, the server treats .html and .HTML as two entirely different files. Want to keep in simple? Try to stick with lowercase letters in all file names and extensions.


Uploading your files in the correct mode (ASCII or Binary)?

Uploading in the wrong format for images or binaries will result in a strange mess appearing in place of the file.  For CGI scripts, this mistake has to be the most common cause of that annoying error known as the (Server 500 Error - Malformed Headers), or something to that lovely extent. While this can be the result of many various programming errors, the most popular amongst new users are uploading their scripts in the "WRONG" format. Your cgi scripts "MUST" always be uploaded in ASCII mode. Alternatively, if you upload an image or .exe file, it must be done in "BINARY" mode.


The difference between ASCII and BINARY?

In short, html or text based files are supposed to be transferred in ASCII mode. Uploading them in Binary mode will append ^M's to the end of every line. In most cases this is OK with html files, because your browser will ignore them. BUT, with other text files such as cgi scripts, uploading them in binary will damage them, thus causing a (server 500 error). This is because binary mode has added ^M's to the end of every line, which are not supposed to be in the program. This of course, is what causes the additional message of (Malformed Headers), which often displays at the bottom of the "Server 500" message when a CGI script has crashed.

Once again, BINARY mode is used for transferring executable programs, compressed files and all image/picture files. If you try to upload an image in ASCII mode, you will observe a strange mess appearing on the page where the image is supposed to appear. ASCII mode in this case, has corrupted the binary coding in the jpeg or gif image. If this happens, just re-upload it in the Binary format
 

Setting your FTP client to automatically detect ASCII and Binary file transfers:

Most FTP programs have "AUTO" mode, which will tell the FTP client to automatically detect the file type you're transferring and will select the appropriate mode. By default, most FTP programs will attempt to transfer everything in binary mode, but when "Automatic" is selected, the FTP client will check a list of known ASCII extensions, (for example, .pl, .cgi, .txt). If it detects one of these extensions, it automatically switches to ASCII mode.

By Default, most of the well-known files to be uploaded in ASCII are already entered, however you can manually add additional extensions that you would like to transfer in ASCII mode by selecting the feature called "Extensions." Here, you can add any additional extensions that will cause the FTP client to toggle to ASCII mode automatically upon detecting an extension entered in its list. Remember, you must set your transfer mode to "Automatic" for this to work.
 

File types and what they represent:

Various file types can effect both the behavior of your files, as well as how the server treats them. While there are numerous file extensions, which represent a host of various file types, we'll stick to the basic ones in this quick overview:

The .html file:

This is one is the most commonly used and the one most of you are already familiar with. Html stands for (hypertext Markup Language). Essentially, it tells the server, as well as the hosting browser to process and display the .html coding in a way, which is meaningful to the end user through a browser.

The .htm file:

Many of you have probably noticed this newer extension appearing in place of the traditional .html one. In short, .htm is most often created, and or generated from the Microsoft FrontPage web editor. The two are essentially the same and provide the same basic purpose. Unless you're using FrontPage, you will probably use the .html extension at the end of your web pages.

The .gif and .jpg file:

Most commonly used because of its good compression in web page images. Generally, .gif files are the fastest loading, as they remove a lot of information, which is not required to maintain image integrity, but to a point however. .jpg will allow more flexibility in compression and quality settings, however it can also result in larger files.

The .CGI and the .pl file:

.cgi and .pl are most often used for perl scripts. Perl scripts are small text based programs, which are executed on the server end, and will perform a host of interactive functions for a web site. In short, when a .pl or .cgi file is called, it tells the server to process it using the "Perl Interpreter." The Perl Interpreter understands the programming within the script, and will perform the set of sub routines, which will yield your desired effect. This desired effect could be anything from a simple web page counter, to more complex programs such as discussion forums, e-commerce platforms, to online auctions. In many cases, you can download these "ready to go" scripts for free, and in others you may have to purchase them.
 

FrontPage and FTP:

If you're planning on using Microsoft FrontPage to manage your web site, there are a couple of issues or things you may want to keep in mind:

There are two worlds. The General Unix hosting world, and the Microsoft world. While this is not necessarily a bad thing, Microsoft had indeed decided to play by its own rules.   As a result, FrontPage does not always conform to the rules of Unix, so you should be extremely careful when accessing a FrontPage web via FTP.  It's easy to damage the FrontPage web, as well as it's associated server extensions, and if it happens, you may loose the ability to administrate it from your FrontPage Explorer. To avoid problems like this:

• Do not alter, or delete files that are part of a FrontPage web
• Do delete, move, or alter directories ending in _vtf. These are the FrontPage extensions

The ultimate solution:

If possible, try to create your FrontPage webs in sub-directories of your root. For example, http://www.yourdomain.com/home. This way, you can safely FTP into your root account to perform other tasks, while avoiding the FrontPage webs, which are safely out of the way in their own separate homes. Remember! DO NOT delete any folders, which end in _vtf! This will kill your FrontPage web, and we'll have to reinstall the extensions for you.

Next:   Using CGI programming: