Install application software under FreeBSD system

FreeBSD has a variety of precompiled packages, ranging from mathematical operations to system maintenance, from image processing to internet service programs. The reason why you can have such a rich software, in addition to UNIX itself is a very popular development platform, the other is important because each UNIX provides advanced language C as a standard development language, and C language is highly portable, And with the popularity of Unix it became the most important programming language.

Because Unix runs on many different platforms, and binary execution files on different platforms only contain machine instructions on this platform, the application on one platform cannot run directly on another platform. But in the Unix world, with a common programming language C and the same system call, the C code for programs on different UNIX platforms is essentially the same, and for a UNIX-developed application, it's easy to migrate to other UNIX systems. Traditionally installing a variety of applications on UNIX is typically in the form of source code, requiring an administrator to manually compile the installation, which requires the administrator to be familiar with the C language and its development tools. However, this is a cumbersome task after all, especially for users who are unfamiliar with C language. As a result, UNIX has developed a number of mechanisms for the direct installation of binaries, and FreeBSD also provides packages collection── a management and installation of a precompiled package mechanism to help users manage a variety of application software, So that users do not need to understand the C language and its development tools, but also the normal application software installation and management.

Categories of application software

Copyright issues such as authenticity and piracy are always one of the topics that computer users need to consider when installing and using application software. Many computer users always think that the copyright of the software is similar to CD-ROM, tape, not the original is pirated. However, this is not absolutely the case, the vast majority of software developers tend to make their own development of the program to be used by as many people as possible, when software developers do not use software as a profit for the purpose, there is no restriction on the application of software, or very tolerant of restrictions. Other users are free to use the software without having to consider copyright issues.

Because of the different purposes of software developers, the copyright protection methods used for their software are different. Some developers develop software for their own personal interests, needs or beliefs, want their software to be used by more people, have no or no time to profit from the software, and therefore encourage others to use the software. Some developers develop software for profit purposes, so strict copyright restrictions are used. Depending on the copyright restrictions of the software, the application can be divided into two categories:

Common domain software and free software

The authors of these software do not impose any restrictions or restrictions on copyright, and software belonging to this category usually provides the source program, allowing users to freely use the software and modify it arbitrarily. The software included in the FreeBSD system is in this category, so users do not need to consider the use of FreeBSD copyright issues. The public domain software does not have any restrictions on copyright, it can be considered as a waiver of copyright software. Many public domain software is developed by research institutes and universities, but is also used by commercial companies in their own systems, when commercial companies use their own copyright notices, and users are not free to use the software.

In order to protect software from misuse by commercial organizations, the Free Software Foundation (Stallman) has used the GNU Copyright license to protect users ' right to use the software freely, which permits the use of free software for commercial purposes, but must allow the user the right to be freely used, copied and modified. Under this license, the GNU software can be sold, but it must also include its source program for the user to modify (or provide when requested by the user).

The GNU Software license is not the only free software license claim, and the BSD license used by FreeBSD is another important copyright license. The BSD license is looser than the GNU license. BSD licensing only requires that the disclosure of the relevant author's information be maintained, with fewer restrictions on business use. In addition, there are X's copyright license and so on. Because the GNU Software license is the most famous and perfect, many non-free Software Foundation software also uses this license to protect the copyright of its own software.

In fact, this kind of software plays a very important role in the development of computer, they often first realize many new ideas, new functions, promote the development of software technology. Free software is no more functional, efficient and reliable than commercial software, and some software is even better than similar commercial software, the only problem is that free software does not provide technical services, only with the software to provide some electronic documents, users need to learn to install and use themselves. Of course, free software usually has a corresponding commercial version, the difference lies in the provision of commercial technical services support.