Common commands and instructions for Linux operating systems (1)

Command format:

Command option Parameters

Options: Specify the execution characteristics of the command

Long options

Short options: can be combined with

Parameters: Specifying the Action object of the command

Command type

Internal command, built-in, internal

External command: The file under a path corresponds to

Type: View command type

External command Invocation procedure

Find commands in Environment variables

View environment variable path: Printenv,path: colon-delimited path

If the user invokes the command, the shell first looks at the hash table, and if it has been called, there will be a cache in the hash table. If this is the first time, there is no such entry in the hash table, and it is located under Path path.

# pwd: View current directory

# ls: Lists files under the specified path

-L: Long format display

File type: 1 bit

-: Normal file

D: Catalogue

L: symbol (soft) connection

B: Block device files

S: Socket file

P: Command Pipeline file

C: Character device file

File permissions: 9-bit, 3-part, rwx (read, write, execute)

Number of hard links to files

Document owner

Group of file genera

File size: Unit default byte

Timestamp: Last Modified time

Access

Modify: Content

Change: Properties

-D: View catalog files

-A: View all files (including hidden files starting with.)

. Represents the current directory: represent the parent directory

-H: Unit conversion

-A: Do not display. All files beginning with

-I: Displays the index node number of the file

-R: Show files in reverse order

-R: Recursive display of files

CD: Switch directories

CD-: Switch back and forth in the current and previous directory

cd~: Switch Home directory

CD: Switch home directory

SU: Switching users

Su uername: Half switch

SU-L Username: Full switch

Exit: Switch Back again

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Common commands and instructions for Linux operating systems (1)