Linux
-
What is linux?
Linux is a free-to-use and freely spread Unix-like operating system. It is a multi-user, multi-tasking, multi-threaded and multi-CPU operating system. It can run major UNIX tools, applications, and network protocols. It supports 32-bit and 64-bit hardware. Linux inherits Unix's network-centric design philosophy and is a multi-user network operating system with stable performance. -
The characteristics of the Linux system?
Stable system: For example, it is common for the host with Linux installed to run continuously for more than a year without any downtime and no need to shut down. My windows system had a black screen when it was turned on this morning, and it was restored after forcibly shutting down, for unknown reasons.
Security And quick fixes for vulnerabilities: Linux is used by many computer masters, so there are many maintainers, and updates and maintenance are fast. Windows is used by everyone, and does not open source,
multi-task, and multi-user: you can plan on a Linux host Different levels of users can be created, and the working environment of each user can be different when logging in to the system. In addition, you can allow different users to log in to the host at the same time to use the resources of the host.
User and user group planning: On a linux machine, files can be Divided into three categories: readable, writable and executable (these attributes can also be set on windows, and will be written in the future windows blog on the command line). In addition, these attributes can be divided into three categories: the file owner. , The user group to which the file belongs, and other non-owners and user groups, which have good confidentiality for the project or other project developers.
Relatively little system resource occupation: this is the most eye-catching place, any one currently on the market Personal computers can be used to build a host serving hundreds of people using Linux.
Customizable tailoring and porting to embedded platforms (such as Android devices)
. Various graphical user interfaces (such as GNOME, KDE) are available.
1. High degree of modularity. The
Linux kernel design is very delicate, divided into five parts: process scheduling, memory management, inter-process communication, virtual file system and network interface; its unique module mechanism can realize some modules in real time according to the needs of users. Inserted or removed from the kernel, the Linux system kernel can be tailored to be very small, which is very suitable for the needs of embedded systems.
2. Open source code
Since the development of the Linux system has been closely integrated with the GNU project from the very beginning, most of its components come directly from the GNU project. Anyone and any organization can use Linux source code freely as long as they comply with the terms of the GPL, providing users with maximum freedom. This is also good for embedded systems, because embedded system applications are very different, designers often need to modify and optimize the source code for specific applications, so whether the source code can be obtained is crucial to the development of embedded systems . In addition, the software resources of Linux are very rich. Almost all common programs can be found on Linux, and the number is still increasing. All this makes it very easy for the designer to carry out secondary development on its basis. In addition, since the Linux source code is open, users do not have to worry about security risks such as "back gates".
At the same time, the open source code provides great convenience to various educational institutions, which also promotes the learning, promotion and application of Linux.
3. Extensive hardware support
Linux can support microprocessors with multiple architectures such as x86, ARM, MIPS, ALPHA and PowerPC. It has been successfully ported to dozens of hardware platforms and can run on almost all popular processors.
Because there are many developers around the world contributing to the expansion of Linux, Linux has an extremely rich driver program resources, supports various mainstream hardware devices and the latest hardware technology, and can even be used without the processor of the storage management unit MMU. All of these have further promoted the application of Linux in embedded systems.
4. Good safety and reliability. The
kernel is efficient and stable. The efficiency and stability of the Linux kernel has been verified by a large number of facts in various fields.
A large number of network management, network services and other functions in Linux enable users to easily build efficient and stable firewalls, routers, workstations, servers, etc. In order to improve security, it also provides a large number of network management software, network analysis software and network security software.
5. Have excellent development tools
The key to developing embedded systems is to have a complete set of development and debugging tools. The traditional embedded development and debugging tool is the in-circuit emulator (In Circuit Emulator, ICE), which provides a complete simulation environment for the target program by replacing the microprocessor of the target board, so that the developer can understand the program very clearly The working status on the target board is convenient for monitoring and debugging the program. The price of the in-circuit emulator is very high, and it is only suitable for very low-level debugging. If you are using embedded Linux, once the software and hardware can support the normal serial port function, even if you don't need an online emulator, you can develop and debug well, thus saving a lot of development costs. Embedded Linux provides developers with a complete tool chain (Tool Chain), which can easily implement debugging at various levels from the operating system to the application software.
6. There is a good network support and file system support
Linux has been inseparable from the Internet since its birth, supports various standard Internet network protocols, and is easy to transplant to embedded systems. At present, Linux supports almost all mainstream network hardware, network protocols and file systems, so it is a good platform for NFS.
On the other hand, because Linux has good file system support (for example, it supports Ext2, FAT32, romfs and other file systems), it is a good platform for data sharing, synchronization and copying, which lays the foundation for the development of embedded system applications. solid foundation.
7. Fully compatible with UNIX
At present, the tools and utilities included in Linux can complete all the main functions of UNIX.
But because Linux is not designed for real-time, this has become the biggest regret of Linux's application in real-time systems. However, many free software enthusiasts are making unremitting efforts to this end, and many results have been achieved.
-
The characteristics of the win system The
intuitive and efficient object-oriented graphical user interface is easy to learn and use. Both the Windows user interface and the development environment are object-oriented. This mode of operation simulates the behavior of the real world and is easy to understand, learn and use. -
The difference between Linux and win
Windows platform: the advantages of quantity and quality, but most of them are paid software; Microsoft officially provides important support and services.
Linux platform: most of them are open source and free software, users can modify, customize and republish, because they are basically free Financial support, some software quality and experience are lacking; all Linux developers and free software communities around the world provide support
·Security
Windows platform: Patching and installing system security updates twice a day, there will still be viruses and Trojan horses, all users feel it yourself.
Linux platform: It is impossible to say that Linux has no security problems. It will not be infected with viruses or anything. This is a point where the benevolent sees the benevolent and the wise sees wisdom. Relatively speaking, it is safer than the Windows platform. You can also use Linux. No need to install anti-virus software.