Record Learning Day Fourth---Linux basic command 1

Recently a little busy, or to strengthen self-control and squeeze time.
One: Linux system
The Linux GUI is just an external software, with and without all.

Ide:
DLL files under windows are dynamic Connection libraries
Linux. So is a shared object

II: Linux Common commands
User name, User ID
Authentication mechanism: Authentioation
Authorization: Authorization
Audit: Audition (log)

Command prompt:
Command:
Magic number: Magic numbers such as #! /bin/bash

LS: List listing
Path mapping: Why use a path: A hierarchical structure helps you find. This mechanism becomes the file system.
The Linux directory structure is inverted tree type. From the root, look for an absolute path, relative to the current position, relative to the path.
FHS:
is the file name data? Where do you put the file name? Where do you put the data?

Pwd:printing working directory displays the current directory

Ls:
-L: Show full information

File type: the
-: Normal file (f)
D: Catalog file
B: Block device files (blocks)
C: Character device file (character)
L: Symbolic Link files (symbolic link file)
P: Command pipe file (pipe)
S: Socket file (socket)

---------: File Permission bit: 9-bit, every 3-bit group, rwx read-write run.
File Hard link count:
Owner of the file
Genus Group of files
File size (size): Unit bytes
Timestamp (timestamp): Last Modified Time
accessing (Access):
Modified (Modify): File content changed
Change: metadata, meta data
Filename

-H: Do unit conversions
-A: Displays all files, including hidden files that begin with a dot
.: Indicates the current directory
.. : Represents the parent directory
-A: not shown. and.
-D: Display the directory's own properties

Each file has a numeric representation called the index node, which is the nodes. -I display.
-R: Recursive (Recursive) display

Cd:change Directory: Switching directories
Home directory:
CD-: Pre-switch directory and current directory

Command type:
Built-in commands:
External command:

Environment variables: named memory space
Variable assignment:
Define the user's current environment
PRINTENV: Display Environment variables
Path: Paths
After the first lookup, the path exists in the cache, hash. Find in the key value team can reach the O (1) standard.

Type: Shows which type the specified command belongs to

Record Learning Day Fourth---Linux basic command 1