Title, Appunti di informatica libera. Author, Daniele Giacomini. Publisher, Systems Comunicazioni, ISBN, , Length, Appunti di informatica libera by Daniele Giacomini at – ISBN – ISBN – Systems Comunicazioni – Softcover. which makes available automatically a swap file for the virtual memory. Appunti di informatica libera Copyright © Daniele Giacomini.

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Software is a code protected from copyright laws, similarly to what happens for literary works. Usually, the contract that rules the use of software is the license ; is always important to know deeply the terms of the license agreement for the software you intend to deal with.

Software always has an owner, except for public domain software which is covered later in this bookwhich is such because he “owns the copyright “. This owner can be the original author or maybe another holder which has gained the rights with a contract.

The holder of the copyright becomes the owner of the work. Use of the software can be granted for free liberaa upon a payment. Paying does not mean “purchasing” the software, but just dealing with it according to what is written in the license.

Nature of the software is comprised of two different parts: The first one is human readable, while the second one is suited for machine execution and not for reading. Since only the executable part is needed to make software operate, software copyright preservation laws that exist in many countries do permit distribution of the executable code alone, allowing the copyright owner to keep the source code hidden.

Following the same path, laws in these countries tend to put an illicit mark over reverse engineering of the software. The latter is the study of the executable code geared towards learning how code operates.

In many countries you may also be able to patent algorithms and other concepts tied to software. This way, the patent doesn’t allow the use of the algorithm or protected idea without an explicit authorisation from the owner of the copyright.

Free software is such if it does allow usage by everybody, copy and distribution of it, both in its original form and its modifications, for free or even by selling it. Free software can be such only if it’s offered along with source code.

To this extent someone said: It’s important to note that “freedom” of free software is not in the price – which can also be requested for the distribution service – but the possibility to use it without restrictions, to copy it as many times as you want, to distribute it and to modify it and even distribute the modified copies.


Some people prefer to use the “Open Source” tag to identify free software in the terms we have described above. Freedom 1, freedom to study and learn how the program operates and the ability to modify it to best suit your own needs in such a case source code is needed.

Freedom 3, freedom to improve the program and to distribute such improvements also for this one we need the source code. Software which can not be sold, even though satisfying the four basic concepts listed here is not going be considered free software in this written work.

Appunti di informatica libera

Public domain software is software without copyright. On its own this software it’s free, but since it has no copyright it doesn’t have a license either, so anybody is free to do whatever he wants with it, even take ownership of the rights.

This means some copies or variations of this software are no more free. The word copyleft is an invention and represents the copyright of who, while defending his rights as the author, wants to defend freedom of his work, imposing that the original version of his work and derivated ones are kept free.

Programming Tips and Tricks: Appunti di Informatica Libera [pdf]

Shortly, a license belonging to the “copyleft” category blocks additional restrictions applied to it from who is going to redistribute the software modified or original whatever at the moment. Free software is not necessarily copylefted and this happens when the license does not explicitly forbid applying additional restrictions from who redistribute the software.

To use software of this kind it’s important to check carefully the terms of the agreement concerning the particular copy or version of the software we have. Software is not free when all the minimal requisites to classify it as such are not satisfied.

Free Book: appunti di informatica libera

It’s a good thing to remember that price is not a thing that limits freedom and that other details are much more important.

Also this time, it is worth listing some definitions for non-free software. Semi-free software is software that allow usage, copy, modification and distribution even after a modification for whatever reason except to make profit out of it.

In other words we could say that is free software with a limitation on usage and distribution for profit. This is a detail that must not be forget. Proprietary software is the one that is nor free neither semi-free. Usually, to deal with it it is necessary to obtain a special permission, that most of the time limits its usage to just one computer or a well-defined environment.


The freeware word is not tied to a strict definition, but usually refers to software that is freely available but doesn’t come along with the source.

It can be copied and used but not modified. Meant this way the “free” prefix is only used to spot that there’s no price set on it, but is fairly different from freedom, which asks for more requisites. With the shareware word we refer to papunti software that you are required to buy after a trial period even if it can be freely distributed.

Ilbera to the various classifications explained in this chapter, commercial software is such, only because it’s sold for profit. One of the basic elements of free software is the possibility to sell original or modified copies to make profit out of it.

Following this subtle difference it is important to spot out the difference of proprietary software from commercial software because they’re not the same thing. To better understand or mess up things as well, we can add that both non-free and non-commercial software do exist. It is worth pointing out here some licenses that are not born from the Free Software Foundation.

The original Artistic license is by most people considered a bad formulated license, too indormatica and thus not good for preserving software freedom.

Under this perspective it is not included in the free software category. To put a remedy in the holes of the Artistic license, a new revision called Clarified Artistic License was developed. The original BSD license contains an explicit reference to the Berkeley university and explicitly states that the name cannot be used for advertising. Even if this concept doesn’t create any problem for software usage, it is not convenient to adopt this license if you don’t have such a need.

«a2», ex «Appunti di informatica libera», ex «Appunti Linux»

Trying to avoid this little disadvantage different modified versions of this license have been created. Unfortunately, a neat libwra for this license does not exist and people tend to simply name them BSD licenses, feeding confusion that should be better to avoid. Appunti di informatica libera There’s too much confusion around the BSD acronym, too many licenses similar to the Berkeley one are released under its name.