Chapter 2. How does Free Software affect Linux?

Table of Contents

Introduction
Free Software
What are Software Licenses?
What Licenses Exist?
Free Software isn't Non-Commercial
So Linux is Free?
Development Model
Multi-Project Development
Transparent Development
Fast Release Cycles
Large Documentation Base
Software Life Cycle
Open Standards
File system Hierarchy Standard
Linux Standard Base
Free Desktop Specifications
Exercises
Further Resources

Introduction

The Linux OS has become increasingly popular mainly due to the freedom it allows (and of course also the low or zero-fee price of the entire operating system). In this chapter we see how these freedoms come to life and how they are protected and sustained.

We also take a look at the development model used by free software projects in general because it is a major result of said freedoms, one that makes free software projects often more interesting than closed-source commercial software projects. The development model is also one of the major strengths of free software.

Free Software

If we take a step back from all technical aspects, Linux differs from the closed-source commercial software in an important aspect: licensing. Licensing is what drives free software...

What are Software Licenses?

Software is someone's intellectual property. Intellectual property is a heavy word that shouldn't be interpreted to anything else than the result of some effort to create something that is not a plain copy. If you write some text, the resulting text is your intellectual property (unless you've copied it from somewhere).

Intellectual property is protected by law. Copyright protects your intellectual property by prohibiting others to copy, adapt, reproduce and/or redistribute your ``thing'' without your consent. Mind you though that not every intellectual property is copyright protected and copyright differs from country to country. An example of intellectual property that isn't copyright protected is a mathematical method: even though the inventor of the method had to ponder years and years on it, his method isn't copyright protected (but if he wrote a text about this method, the text itself is). Copyright is automatically assigned: it doesn't cost you anything and it is broadly accepted.

Another protection is a patent. Patents are (or should be) granted to new inventions who are not known to the public at the time of the patent request. Patents are often used to protect intellectual property that isn't protected by the copyright: methods for doing stuff (including medical compositions). Sadly, the industry is often abusing patents for much more when they have a patent with a broad action field: the patent covers too much, allowing the company to force others not to use a method they actually do have the right to use. Also, both the request and the patent grant are very costly and only larger companies have the abilities to obtain (and protect) several patents. Smaller companies or individuals don't have the means to obtain a patent, let alone protect themselves in a court because they might have used a method that is described in one or more patents.

I use the word abuse because companies often get patents for methods that are broadly used or are so silly that you'd wonder what patent office (patent requests are - or should be - checked for their validity before they are granted) has granted those patents.

I'll abstain from elaborating on this (politically sensitive) topic more and move on to software licenses. A software license is a contract between you, the software user, and the software copyright owner. It tells you what you can and cannot do with the software. Any software that is not licensed is fully copyright protected, meaning you shouldn't even have it, let alone run it.

Most commercial-grade licenses are often called the EULAs, or End User License Agreements. They usually say what you are allowed to do with the software (often including what you are allowed to use the software for). The EULAs more often stress what is denied rather than allow anything. One of the many topics is redistribution of the software. Most EULAs explicitly disallow redistribution.

Linux (and free software in general) is different. The accompanying license grants you the right to copy the software, obtain the source code, modify it and redistribute it (with or without modifications) and even sell it. Because there are many variations possible there are many popular licenses.

What Licenses Exist?

I'll list a few of the most popular licenses here, but be advised, there are more than 800 licenses around. Many of those licenses are quite similar (or are exactly the same) and the free software community should start to consolidate all those licenses in a much smaller set. Sadly, they haven't done so yet. Luckily, the 90-10 rule here applies: 90% of all free software uses 10% of the free software (or other) licenses. The other licenses are only marginally used, sometimes just for a single application.

Public Domain

When software is placed under the public domain, you're free to do whatever you want with it: the author waves any right he can to allow for full freedom of his software.

MIT License and some BSD-like Licenses

The MIT license and some BSD-like licenses are almost like the public domain, but ask you to keep the copyright notice intact. This is a very popular license because the author allows you to do whatever you want as long as you keep his name on the product copyright notice as well.

GPL

The GNU Public License is the most widely used free software license, but for some people also the most restrictive free software license. The GPL tells you that you can do whatever you want with the software, as long as you provide the source code of your modifications to whoever you distributed the modified version to and as long as this modification is under the GPL as well.

The Linux kernel is GPL licensed.

OSI Approved Licenses

An OSI approved license is a license that adheres to the Open Source Definition written down by the Open Source Initiative of which the following points are a free interpretation:

  • free redistribution

  • source code available

  • modifications are allowed (including redistribution)

  • no discrimination (people, fields ...)

FSF Approved Licenses

An FSF approved license adheres to the Free Software definition written down by the Free Software Foundation of which the following points are the core of the definition:

You should be free to ...

  • run the program for any purpose

  • study how the program works and adapt it to your needs

  • redistribute copies

  • improve the program and release your changes to the public

Free Software isn't Non-Commercial

Free software is often perceived to be a pure hobbyist project: it would not be commercially viable to bring free software to the enterprise world. After all, if software is freely available, what kind of profit could a company make from it. Nothing could be further from the truth...

It is true that free software requires a different look on software in a commercial environment (including companies). Companies who use software want to be assured that they have support for the software when things go wrong. They often close (costly) support contracts with the software company where service level agreements (abbreviated to SLAs) are defined. Based on these contracts, the company has the assurance that if certain services become unavailable, the supporting company will do whatever it can to bring the service back or, in some occasions, compensate the financial damage that the downfall has caused.

Most of the time, these support contracts are closed with the software company itself because it has the most knowledge of the software (as it is probably the only company with access to the software code). Sadly, as good as this reason is, companies don't look at free software ``because there is no support''. This isn't true; support for free software is still (commercially) available, but most of the time not from the creators themselves. And although this scares the companies, the reason why this support is still as good as with off-the-shelf software remains the same: the supporting company has access to the source code of the tool and has professional knowledge about the tool. It probably has developers in the software project itself.

Companies that sell software are of course often against free software. When these companies major income depends on the sales of their software, it would not be viable to make the software free. If they would, competing companies would have full access to the source code and improve their own product with it.

I don't think this is a disadvantage though. Software companies should use their main strength: knowledge about the tool. As mentioned before, other companies often want to close support contracts to ensure the service that the software delivers; if the software company creates free software, this wouldn't change. For many software companies, support contracts are the main source of income.

It is still possible to sell free software; some pioneering companies are payed to made modifications to free software because companies don't have the resources to do so themselves. These companies can keep the modifications private if the free software license allows this) but can also bring these modifications to the public by contributing it to the software project itself.

A major proof of this is the acceptance of free software by major software players such as IBM and Intel, and the emergence of new software players that build their business upon free software, such as RedHat.

However, don't think that every free software project is enterprise-ready or that you will be able to find (paid) support for every software project. You should carefully check out every software title you want to use if you want to use software, free or not. For end users, distributions help you to pick software. If a distribution packages a certain software title, it feels that the software title is stable and well supported.

So Linux is Free?

Yes, Linux is free. It is certainly free in the sense of ``free speech'' and although most software titles are also free in the sense of ``free beer'', you shouldn't be surprised to see distributions you can or have to pay for. In that case, you can be paying for the software medium (the burned DVD), accompanying printed documentation, 30-day installation and usage support or for the resources that the distribution has to acquire itself (like infrastructure).

Most distributions have free downloads with online documentation and wonderful community support (active mailing lists or Internet fora), which is why Linux is that popular: you can download, install and use several distributions to decide which one is best for you. You can try the software (without loosing any functionality) and you don't even have to pay for it to continue using it (as is the case with shareware). Gentoo is one of those distribution projects. Such distributions get their financial backing (for infrastructure and organisational needs, including juridical support and bureaucratic paperwork) from user donations or sales of pressed DVDs. Companies also tend to support distributions financially or with hardware / bandwidth donations.

Some distributions are only available when you pay for it. In that case you often pay for the support or for additional software in the distribution which isn't freely available. A popular distribution is RedHat Enterprise Linux, a Linux distribution specifically targeting companies who want to set up Linux servers. You don't just pay for the support, but also for the resources that RedHat has put in the distribution to make it certified for other software (such as Oracle and SAP) so that you can run (with support from the software company) this software on your RHEL installations.

It is important however to understand that distribution projects only develop a very small part of the software that you install on your system. Most software comes from other free software projects and these projects often don't get gifts from the distribution projects. Nonetheless they do face the same problems as any other (larger) free software project: bureaucratic paperwork, juridical support, infrastructure needs, ... So it comes to no surprise that these projects also have the same income streams as the distribution projects: user gifts, commercial sponsorship and software / support sales.

Development Model

Due to the nature of free software projects, you'll find that it has quite some differences with closed-source commercial, off the shelf software...

Multi-Project Development

One distribution provides an aggregation of software. Each of those software titles is built by a software project which usually differs from the distribution project. Hence, when you install a distribution on your system, it contains software from hundreds of software projects around the world.

So to obtain support for a flaw you found, or an issue you come across, the first place to seek support would be the distribution, but chances are that the distribution will put the support question upstream, meaning that it forwards the request to the software project that develops the software you have an issue with.

Transparent Development

Free software is usually developed transparently: if you are interested in the development of your favourite software title, you can quickly find out how its development works and how to participate.

Usually, software projects use a concurrent versions system such as Git or SVN to keep the source code in. Such systems allow for dozens (or even hundreds) of developers to work on the same source code simultaneously and keep track of all changes that have happened (so they can easily be reverted). This isn't just for free software projects - almost all software projects use such a system. However, free software projects usually allow non-developers to see the progress of the development by giving them read-only access to the system. This way, you can track every change to the software personally.

To discuss the future of the software, or to take software design decisions, most free software projects can't use real-life meetings: their developers are scattered around the world. A solution to this problem are communication systems such as mailing lists, IRC (chat) or forums (Internet or Usenet). Most of these communication systems are also open for non-developers to participate in the discussions, meaning that end users have direct communication with developers.

The latter has a major advantage: changes requested by the users are directly communicated to the developers so that misinterpretation is less frequent, allowing for projects to update their software more accurate and frequent.

Fast Release Cycles

Larger free software projects have hundreds of contributors and several dozens of developers. Those developers are very motivated to work on the software by passion. If they weren't, they wouldn't be working on the software as there usually is no other incentive to work for (such as a nice pay check) although it must be said that there are software projects (and they aren't small in numbers) who have paid developers as well. As a result, the software is quickly progressing and new features are added quickly (some projects even have new features on an almost daily basis).

To make sure that new features and fixes are tested properly, software development snapshots are communicated to a broad community of testers and stable snapshots are often released to the general public as a new release of the software. Different release types are commonly used in free software environments:

  • nightly snapshots are extracts of the source code at a certain period in time which are built and put online for everyone to use. These releases are automatically generated and are bleeding-edge as they represent the state of the software title only a few moments ago. They are highly experimental and only meant for developers or experienced contributors

  • development releases are intermediate releases, similar to nightly snapshots, but somewhat more coordinated by the developers. They usually have a ChangeLog which lists the changes in it since the previous release. Such releases are meant for experienced contributors and testers who don't mind the software to be broken from time to time.

  • beta releases contain a preliminary vision of how the final release will look like. It might not be fully stable or complete but individuals who don't participate in the frequent tests can try and see if the new release would still work for them and contain the fixes they requested. Beta releases are also important for distributions as they can now start developing packages for the software so that they are ready when the final release of the software is made.

  • release candidates are proposals for final releases. They contain the software such as the developers would like to release it. They now wait for a certain period so that the testers and general public can run their tests to ensure no bugs are in it any more. New features aren't added to the software now, only bug fixes. When no new (or major) bugs are found, the release candidate is converted to a new release

  • stable release are the final releases of the entire development process. These releases are now used by the users and distributions and the entire development process can start over.

Stable releases also tend to be released in specific gradations, reflected by their version number. A popular numbering scheme is x.y.z where:

  • x is the major version; this version number is only updated when the software has been substantially changed. Often such releases also require all packages that depend on it to be updated as well because they might use features or libraries that are changed.

  • y is the minor version; this version number is updated every time the software has been updated with lots of new features

  • z is the bugfix version; this version number is updated whenever mainly bug fixes have been added to the software

As an example I'll list the release dates for the LibreOffice 5.1 and 5.2 releases (based on the modification times of the source directories, which aligns nicely with LibreOffice's ReleasePlan.

  • 2016-01-27: LibreOffice 5.1 is released

  • 2016-03-03: LibreOffice 5.1.1 is released

  • 2016-04-01: LibreOffice 5.1.2 is released

  • 2016-05-05: LibreOffice 5.1.3 is released

  • 2016-06-15: LibreOffice 5.1.4 is released

  • 2016-07-29: LibreOffice 5.1.5 is released

  • 2016-07-30: LibreOffice 5.2.0 is released

  • 2016-08-25: LibreOffice 5.2.1 is released

  • 2016-09-26: LibreOffice 5.2.2 is released

  • 2016-10-21: LibreOffice 5.1.6 is released

  • 2016-10-31: LibreOffice 5.2.3 is released

  • 2016-12-01: LibreOffice 5.2.4 is released

The releases follow each other quite closely. The period between the 5.1.0 and 5.2.0 release is around 6 months, and the 5.1 releases continue a bit to guarantee a stable migration for users.

Large Documentation Base

Because the project often can't deliver human, paid support for the software, its success is largely based on the documentation the project delivers. If the accompanying documentation contains all information about the software, experienced or independent users can find all user related answers in the documentation.

Free software projects usually have high profile documentation, often better than the online available documentation of closed-source off the shelf software. Many larger projects even have all this documentation available in several languages. And if you don't find your answer in the project documentation, chances are that one or more users have written independent guides on the software elsewhere.

There are many sites on the internet that link to the various documentation resources and the same problem as with free software itself arises: often you have too many resources making it harder to find the correct document to guide you through your end user experience of the software. However, unlike the plethora on software titles around (making it difficult to find the right software for the right job) it is easier for a user to know if documentation is good or not so there is no need for a ``documentation distribution''.

Software Life Cycle

If you buy software of an unknown, smaller company, you have the chance that after a number of years, the company doesn't exist any more or is taken over and doesn't support that software since. Something similar is true with free software: if the project decides that there aren't enough resources to continue the development of the software (usually due to a shortage on developers) it can stop the development of the software, usually resulting in a drop of support from users as well.

However, unlike the case of the software company, the free software source code remains available to the public. If you desperately need the software to work for you, you can just pick the source code and continue the development of it yourself (or pay others to do it for you). You're also confident that the software will remain free.

If at any time all the copyright owners of the free software decide that the software falls under a different license which you don't agree after, you can take the source code of the moment right before the copyright holders decided to switch the licenses and continue the development under that license (as that software is still under the original license and not the new one). This process (where a group of developers disagree with the development plans of the software and start a new project based on the same source code) is called forking the project.

A well known example of such a fork is the creation of the X.org project, a fork of the XFree86 project which at a certain point in time decided to change their license. The license change wasn't the only reason for that fork: some developers were also unhappy with the development policy on new features and the development pace. X.org rapidly became the most popular X server implementation, and a while later the XFree86 project closed its curtains.

Open Standards

Because so many projects are involved, it is important that each project uses standards as much as possible. Only by complying to open standards can projects easily and efficiently work together. Next are a few important standards or well perceived specifications in the free software world.

File system Hierarchy Standard

The first standard I discuss is the File system Hierarchy Standard, abbreviated to FHS. This standard is used by almost all distributions and discusses the file locations on a Linux file system. One can read the FHS online at http://www.pathname.com/fhs/ but many other resources describe the FHS layout as well.

The file system layout for Unix/Linux is quite different from the file system layout as seen from within Microsoft Windows. Instead of marking partitions by a drive letter, Unix/Linux sees a file system as a tree-like structure, starting with a root and building up through directories and files. You could say that the branches in the structure are the directories and the leaves are the files. If you think you have not encountered a Unix/Linux file system before, think again: URLs that you use on the Internet are based upon this structure. For instance, the URL https://wiki.gentoo.org/wiki/FAQ denotes the resource called FAQ which can be found on the server of wiki.gentoo.org, in the path /wiki. So, / is the root, "wiki" is a branch of this root and "FAQ" is located inside this branch.

Distributions that adhere to the FHS allow their Linux users to easily switch between distributions: the file system structure remains the same so navigation between folders, device files ... doesn't change. It also enables independent packagers to create packages for several distributions at once (as long as the distributions use the same package format). But foremost, it allows Linux users of one distribution to help users of other distributions as there isn't actually any difference between their file system layouts.

The current version of this standard is 2.3, released on January 29th, 2004.

Linux Standard Base

The Linux Standard Base, or LSB sets the layout, binary compatibility, required libraries, required commands and more for a Linux operating system. If a distribution adheres to the LSB standard it can install, run and maintain LSB compliant (software) packages.

Distributions should adhere to the LSB if they want to ensure that they don't deviate from a good Linux standard. As a consequence, the LSB is an effort to ensure that distributions stay similar with regards to libraries, commands ... or in overall, user experience. It is a good effort to ensure that no fragmentation occurs in the Linux world.

Because the LSB is a broad standard, it comprises of other standards, including the aforementioned FHS but also the Single Unix Specification (SUS) which defines how a Unix system should be. However, one cannot say that his Linux operating system is Unix because he would need to certify the OS (which requires serious financial support) and this certification wouldn't last long because the Linux OS changes often.

One of LSBs' largest advantages is that ISVs (Independent Software Vendors) such as Oracle, IBM, Sybase ... can package their software in an LSB-compatible software package which can then be installed on any LSB-compliant distribution.

Free Desktop Specifications

On https://www.freedesktop.org you'll find a set of desktop specifications that are well known in the free software community. Although they aren't standards (as freedesktop is no standards body and the specifications haven't been converted into OASIS or ISO standards) many distributions adhere to them.

These specifications define how menu entries are created and maintained, where icons should reside, but also how drag and drop between different libraries (most notably Qt and GTK+, the graphical libraries for KDE and GNOME) should be made possible.

Exercises

  1. What is the difference between GPLv2 and GPLv3?

  2. Part of LSBs standard is the ELF or Executable and Linking Format, the binary format for executable, compiled code used by various Linux/Unix distributions. Can you find other operating systems that support the ELF format beyond Linux/Unix?

  3. Some people see fast releases as a weakness in the free software community: users are "forced" to upgrade their software more often and even though it is free, it still takes time (and sometimes headaches) to upgrade the software this often. Some distributions tend to help those users by offering stable (both in stability and in version releases) software only. How is this possible?

  4. How is it possible that many distributions allow you to upgrade to the latest version without needing an installation CD or re-installation from scratch?

Further Resources