UNIX virtual machine model
The concept of using and designing virtual machines is an effective way to establish a interactive, robust virtual device. This method can be used to solve many of the problems faced by computer engineers. In the UNIX operating system, the concept of virtual machines and the height of the process model are highly unified. UNIX operating system is one of the most successful use of modern computers and is one of the most respected operating systems. Widely used in Unix makes his virtual machine features all discovered and classified as a real virtual machine. UNIX operating systems use a series of independent processes to complete the user's instructions. UNIX can arrange and configure the process it created to pass and manipulate data. Conceptually, UNIX processes can be seen as a virtual machine because it has many features of virtual machines, which are organic compositions of other three virtual machine models. The UNIX virtual machine obtains similar features similar to the IBM virtual machine model by using the consistent user shell (User Shell), which is similar to the virtual machine of the IBM virtual machine system. The UNIX user housing can be considered a separate virtual machine because each user interface is a separate entity with a complete hardware resource set. The user's shell is like a skilled dispatcher, which generates a new process, boot data flows from one process to another process to complete the user submitted to the user's housing. The outer casing is limited by memory boundary and some shared resource coordinate boundaries, which prevents conflicts of critical hardware devices. However, the user's housing still retains the principle of independent and segmentation in the IBM model.
The UNIX process also has a feature of the Java virtual machine because it utilizes the unified platform library function provided by the hierarchical design of the operating system. The UNIX operating system provides a collection of uniform sets of different library services for the user's processes. The UNIX operating system is a hierarchical design, and each layer provides services and functions for its previous layer. This standardized design allows users to perform their programs on different platforms using a standard function set. This is possible on UNIX using the POSIX standard. This standard is published by the IEEE POSIX project group in "Information Technology Portable Operating System Interface (POSIX ?? Second Part: Housing and Function Program), which specifies the standard of UNIX housing and application routines. Although the code of a particular program still needs to be recompiled on each platform, the program code is truly portable because each subject's UNIX platform supports the same function set.
In the underlying structure of the UNIX operating system, the user's housing also reflects some features of the OSI virtual machine model. The Unix operating system extension of hardware is one of the basic features of UNIX. For example, hardware may use a disk array to provide a large file system. These independent disks are for the user, and the instruction layer passes the user layer command to the hardware or returns the hardware instruction to the user layer.
The Unix virtual machine model integrates all three virtual machine models, generating a very reliable and universal method - create other processes and deliver process output to complete user tasks. In this way, UNIX processes can work as virtual machines. UNIX user processes get user input and then create a range of virtual machines. The output of each virtual machine will be the input of the next virtual machine.
The final result of the data manipulation and output redirection is the completion of the user specified task.
