Linux system Knowledge-system architecture

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Http://www.cnblogs.com/vamei/archive/2012/09/19/2692452.html

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Hardware

Material basis. Including CPU, memory, hard disk, NIC, etc.

Kernel

A computer program that directly manages the hardware. All computer operations are passed through the kernel to the hardware. Including CPU interface, memory interface, hard disk interface, network interface, etc.

System calls

Make the function interface of the kernel into a system call. The system call looks like a C-language function that can be called directly in the program.

Library functions

belong to the application layer, combining system calls into some common functions. Operations such as the allocation of memory are defined as functions such as malloc ().

Shell

belongs to the application layer and is a special application, also known as the command line.

The shell is a command interpreter, such as "Ls-l", which interprets this as "find the LS file in the default path, execute the file, and attach the parameter-l".

The shell acts as a graphical interface before the graphical interface is used.

The shell is programmable and can execute text that conforms to the shell syntax, which is the shell script

Shell down-pass system calls, up and down a variety of applications, at the same time there are many small tools themselves can be used.

UNIX Philosophy: Let each program try to do a small function independently. The shell acts as a "glue" for these small functions, allowing different programs to work together with a clear interface to enhance the functionality of the program.

A shell corresponds to a terminal

Application

is a program. You can invoke system calls, call library functions, and run shell scripts directly.

Can be developed in multiple languages, the most common is C language.

Linux system Knowledge-system architecture