What does CGI-bin mean & what do I need it for

The days of static websites - meaning they consist of a fixed programmed content in the format of Hypertext Markup Language (HTML) - are long gone. Today, programs generate HTML code dynamically from multiple sources such as databases, media, and other files.

In order for a web server to communicate with other programs, all information must be in a defined format. The Common Gateway Interface (CGI) is one of the most popular standards and its task is to enable the error-free and unambiguous exchange of data between the web server and external software.

What is CGI and how does it work?

From the users' perspective, CGI is primarily a function that all web servers commonly used on the internet, such as NGINX or Apache 2, provide. Its main task is to convert data into a universal format for exchange with external programs and to provide methods for their exchange. In this way, the interface ensures that both the web server and the external instances understand the structural layout of the information, can clearly and unambiguously extract the original content, and convert it for internal use. Abstractly speaking, the standard could be described as common behavioural rules, language, and grammar that all parties know and use to avoid errors or misunderstandings in translation between different programs.

How does CGI work?

Specifically, CGI actually consists only of an abstract standard for data exchange. However, in general usage, it often includes a platform that the web server provides for external software to facilitate bilateral communication according to a uniform procedure. In this sense, in many contexts, the abbreviation refers less to the actual standard than to a runtime environment provided by the web server and usable globally within the operating system.

This environment includes, among other things:

• Data channels accessible from both sides in the operating system as common interfaces
• Accessible environment variables with important parameters such as relevant configuration settings and the current status of the web server
• Scripts describing the handling of data, formats, or programs
• Integration into the operating system to manage processes or connections
• Internal content delivery to the web server

An essential feature and one of the key advantages contributing to its popularity is CGI's function as an independent standard. This means specifically that CGI programs can be written in any programming language available on the system and are not tied to a specific operating system such as Windows or Linux.

How to install CGI?

Generally, it is a part of the web server and there is no need to manually install support for it. Only in the case of a dedicated Dedicated Server or Virtual Private Server (VPS), it may be necessary to load a corresponding module into the web server or change its standard configuration to use CGI. Except for rare exceptions, it is included in paid and usually also in free web hosting services as a basic feature and does not require separate setup. It should be noted that the terms of use may vary among individual providers - for example, in terms of maximum size or the potential resource consumption of individual programs.

What is CGI used for on the internet?

As mentioned earlier, modern websites consist of programs or scripts that are often written in a programming language such as PHP, Perl, or Python. They contain detailed instructions on where the content of an HTML document is compiled from. This process offers numerous advantages: texts or integrated media can be centrally managed in a database. Additionally, the software - such as a Content Management System (CMS), forum management, or e-commerce system - generates a unique response for each request, allowing the content to automatically change based on specific criteria such as registered users, guests, customers, or the visitor's origin. CGI provides the ability to use custom programs and any programming language independently of the web server's properties. This is particularly important for languages like Perl or Python, as they are not natively supported by every web server or through modules, unlike PHP (in contrast to PHP).

What are the advantages and disadvantages of CGI?

The main advantages undoubtedly lie in its universal use and availability - as one of the oldest standards for integrating dynamic websites, it is a basic feature of web servers on the Internet.

Other advantages include:

• Easy configuration and setup in local networks
• Simple integration of exotic databases
• Detailed documentation and good support
• Flexible and usable independently of external factors
• Reliability and professional long-term development

However, CGI also has specific disadvantages, with some of the key criticisms being:

• Complex process management and high resource consumption
• Low performance and slow data processing
• Potential security risks from executing and accessing external programs
• Potential security risks from incorrect configuration

Photo: Pexels from pixabay.com