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In order to get your CGI programs to work properly, you'll need to have Apache configured
to permit CGI execution. There are several ways to do this.
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:
ScriptAlias /cgi-bin/ /usr/local/apache/cgi-bin/
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 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.
You could explicitly use the Options directive, inside your main server
configuration file, to specify that CGI execution was permitted in a particular directory:
<Directory /usr/local/apache/htdocs/somedir>
Options +ExecCGI
</Directory>
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:
AddHandler cgi-script cgi pl
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:
AllowOverride Options
In the .htaccess file, you'll need the following directive:
Options +ExecCGI
which tells Apache that execution of CGI programs is permitted in this directory.
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