1.Linux Introductory Introduction

Preparation: Installing a VMware Virtual machine and installing Linux on the CentOS6.5 system (Rhel as well as any derived Linux system), of course, can be installed directly on the native Linux.

1.Linux Introduction

Linux originated from UNIX systems, a system that was released a long time ago by Bell Labs, and later expanded into many commercial versions, and then offered a school version. But the UNIX system at that time can not touch many people, need to apply to large computer room.

Then there was a person (Linus Torvalds), think Unix system so good, but can not everyone use, so they wrote an open source system---Linux.

We need to figure out a concept----Linux is not UNIX.

Linux has been developing very quickly since its inception, but it is likely that people often use Windows as a system. In the client domain, Windows does actually occupy half the market. But on the service side is not the same, currently more than 98 of the world's servers are using Linux systems. But in recent years, in the financial and electrical fields, many Windows-based servers have begun to emerge. And the Linux system is gradually perfecting its desktop system.

Linux has many versions, but these versions are not known as Linux systems and should be called "Linux kernel-based" systems. The kernel is the core program for managing machine hardware (memory, hard disk, I/O, VFS file system, CPU, thread scheduling, and so on).

Because Linux has only one kernel at the beginning, and many new systems are built around the kernel of Linux, the external program is written by invoking the kernel's API.

Linux now has the following versions of the system:
(1) Debian

(2) Ubuntu

(3) Suse/opensuse

(4) RHEL

(5) Red Flag Linux

(6) Centos

(7) Fedora

Format of the Linux version: R.x.y. where R is the most recent version number, X is even when the version is stable, and for odd times for the developing version. Y is the number of bug fixes. Example: 2.2.17, 2.0.23

Basic knowledge of 2.Linux

The knowledge we have to Master is:
(1) Users of Linux
(2) Linux Administrator mechanism (network management, security management)
(3) Hill (Shell) programming
(4) Linux-based system programming (C + +)
Wait a minute......

For servers, the simpler the system is, the more secure (as in the current year's Dos). There are a lot of vulnerabilities after Windows installation, but this is unavoidable.

We basically do not explain the use of graphical interface, only the use of instructions to operate Linux knowledge. General maintenance service side is usually remote operation or real machine debugging, no matter what method, can not leave the console (that is, like the cmd black box in Windows), learn good Linux console operation instructions, it is also an IT practitioners of the necessary quality. We need to keep a firm grasp of the commonly used directives, and for infrequently used queries you can query related documents.

3. Basic knowledge of operating system

General operating systems will include memory management, hard disk Management, I/O processing, VFS file system, CPU scheduling, thread scheduling and so on, we focus on several principles, to facilitate the operation of the operating system more understanding.

(1) FS (FileSystem) file system:
Think of the hard disk as a vacant space, and then divided into a small grid, the record of the small lattice what data stored, how many and so on. This will make it easier to manage data. The size and shape of each lattice is controllable, and the size of the splitter in different formats is called a different file system. Different file systems are incompatible.
The VFS (virtualfileststr) file system, or virtual file system, is a unified interface defined on a variety of different file systems. In its view, all file systems are the same, and all file systems are abstracted. For the program, you only need to program for the VFS, there is no need to program according to different file system.
In general, the VFS System abstracts all the file systems, simplifying our programming (C + +).

(2) Process management
In the earliest Linux, threading was not supported, only the management of the process was supported. But the Linux process is equivalent to Windows threads, which are also lightweight, unlike windows that are heavyweight.

We'll learn more about Linux in the next few chapters, including how to install Java-related programs on Linux and how to develop Java applications on Linux.

1.Linux Introductory Introduction