Linux Basics 2

Copyleft: with the Copyright relative, meaning the user is free to learn, freely modify the source code, can get the source code for any purpose ...

an Droid:

Linux+jvm+java program (because it runs on Java Virtual machine, so its performance is weaker than iOS running directly on the Linux kernel)

IOS :

Free bsd+object-c (Swift)

The Linux Basic Law:

E verything is file (including hardware)

Composed of a number of small programs for a single purpose, combining small programs to complete complex tasks

all configuration data is saved as a text file ( Vi/vim editor)

Try to avoid capturing the user interface (the program executes without interacting with the user to automate the scripting process)

Linux system Level:

Running programs: Dispatching applications through the kernel to hardware execution

User interface: A special application that provides a mechanism or platform for users to run other programs

CLI :

shell, various she ll such as sh,bash,csh, etc    echo$shell linux if is installed. shell, ( echo $ is the way to get the value of an intrinsic variable)

CLI, The user enters the appropriate command

GUI : GR aphic user interface, that is, the graphical user interface, similar to Windows interface, but Windows the graphical interface is cured in the system kernel, and Linux is only an application interface, can not be used, is the user choice.

Linux Common GUI :

Gnome C

KDE C + +

XFCE, lightweight

Terminal:

virtual Terminal: c - 6] 6 virtual terminal    use Span style= "font-family:simsun;font-weight:bold;" >tty command behaves as /dev/tty#

Pseudo Terminal: such as through SE CURECRT , and the other is used under the graphical interface terminal. performance as /dev/pts/#

Physical Terminal: Console port. expressed as/dev/console

Serial terminal: Serial port, serial output character, no need to rely on video card, different VGA expressed as /dev/ttys#

Graphics Terminal: also is a virtual terminal, CT Rl+alt+f7, first time start

Need to enter startx& under Virtual Terminal or start a window again startx--2 &

Bus:

Address bus: Addressing

Control bus:

Data bus

User mode: working on Ring 0

Kernel mode: working on Ring 3

Interruption: inch Terrupt

Hard interrupts: hardware-generated interrupts

Soft interrupts: Interrupts generated by the program (software), from user mode to privileged mode, are implemented by soft interrupts

DMA : D Irect Memory Access

Ma Tadata: Meta Data -- Index Data

I/O equipment is usually divided into Controller and the de Vice two parts. The CPU is implemented by interacting with the controller to control the i/0 device.

OS Features of:

Memory management

Process scheduling

File system

Network protocol stack

Driver Program

Security features-encryption, decryption, etc.

Variable: Memory space with Name

Environment variables used to change variables that use the environment or theme.

Variable assignment:

Format: Variable name = value

``

‘‘

""

PS1:

\u	Current user name
\h	Current host name
\h	The full name of the current host
\w	Absolute path to the current working directory
\w	base name of the current working directory
\&	Prompt

Linux File System:

Case sensitive

All documents

Inverted tree-like structure

A directory is a namespace

Root Fs:linux The system is a single root directory structure, unlike Windows can be divided into multiple partitions.

Current directory (working directory)

Home directory, the directory at the beginning of the user's first login

This article is from the "Let It Go" blog, please be sure to keep this source http://41080138.blog.51cto.com/2587513/1591556

Linux Basics 2