ScriptAlias

The ScriptAlias directive tells Apache that a particular directory is set aside for CGI programs. Apache will assume that every file in this directory is a CGI program, and will attempt to execute it, when that particular resource is requested by a client.

The ScriptAlias directive looks like:

 <font color="#ff0000">ScriptAlias /cgi-bin/ /usr/local/apache/cgi-bin</font>

The example shown is from your default httpd.conf configuration file, if you installed Apache in the default location. The ScriptAlias directive is much like the Alias directive, which defines a URL prefix that is to mapped to a particular directory. Alias and ScriptAlias are usually used for directories that are outside of the DocumentRoot directory. The difference between Alias and ScriptAlias is that ScriptAlias has the added meaning that everything under that URL prefix will be considered a CGI program. So, the example above tells Apache that any request for a resource beginning with /cgi-bin/ should be served from the directory /usr/local/apache/cgi-bin/, and should be treated as a CGI program.

For example, if the URL http://www.example.com/cgi-bin/test.pl is requested, Apache will attempt to execute the file /usr/local/apache/cgi-bin/test.pl and return the output. Of course, the file will have to exist, and be executable, and return output in a particular way, or Apache will return an error message.

CGI outside of ScriptAlias directories

CGI programs are often restricted to ScriptAlias'ed directories for security reasons. In this way, administrators can tightly control who is allowed to use CGI programs. However, if the proper security precautions are taken, there is no reason why CGI programs cannot be run from arbitrary directories. For example, you may wish to let users have web content in their home directories with the UserDir directive. If they want to have their own CGI programs, but don't have access to the main cgi-bin directory, they will need to be able to run CGI programs elsewhere.

Explicitly using Options to permit CGI execution

You could explicitly use the Options directive, inside your main server configuration file, to specify that CGI execution was permitted in a particular directory:

<font color="#ff0000"><Directory /usr/local/apache/htdocs/somedir>
 
 
 
Options +ExecCGI
 
 
 
</Directory></font>
 

The above directive tells Apache to permit the execution of CGI files. You will also need to tell the server what files are CGI files. The following AddHandler directive tells the server to treat all files with the cgi or pl extension as CGI programs:

 <font color="#ff0000">AddHandler cgi-script cgi p</font>
 

.htaccess files

A .htaccess file is a way to set configuration directives on a per-directory basis. When Apache serves a resource, it looks in the directory from which it is serving a file for a file called .htaccess, and, if it finds it, it will apply directives found therein. .htaccess files can be permitted with the AllowOverride directive, which specifies what types of directives can appear in these files, or if they are not allowed at all. To permit the directive we will need for this purpose, the following configuration will be needed in your main server configuration:

 <font color="#ff0000">AllowOverride Options</font>
 
 
 

In the .htaccess file, you'll need the following directive:

 <font color="#ff0000"> Options +ExecCGI</font>
 

which tells Apache that execution of CGI programs is permitted in this directory.