Common commands for Linux operating systems

1. File types

List:ls

Lists, lists

Directories: Files, path mappings

Path: The location from the specified starting point to the destination

FileSystem: File System

List files under the specified path

Catalog: Working directory,current Directory

Pwd:printing working Directory

Ls

-L: Long format

File type: the

-: Normal file (f )

D: Catalog file

B: Block device files (blocks)

C: note Equipment file (character)

L: Symbolic Link files (symbolic link file)

P: Command pipe file (pipe)

S: Socket file (socket)

File permissions: 9 bits per 3-bit group, each group: rwx (Read, write, execute), r--

Number of hard links to files

Owner of the file

Genus Group of files

File size (size), in bytes

Timestamp (timestamp): Last Modified Time

Access: Access

Modified: Modify, Unit is byte

Change: change,metadata, meta data

-H: Do unit conversions

-A: Show hidden files starting with.

. Represents the current directory

.. Represents the parent directory

-A

-D: Display the directory's own properties

-i:index Node,inode

-R: Reverse Display

-R: Recursive (Recursive) display

Cd:change Directory

Home directories, home directories, home directory

CD ~username: Enter the home directory of the specified user

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

Command type:

Built-in command (shell built-in), internal, built-in

External command: There is an executable file corresponding to the command name in a path on the file system

Environment variables: named memory space

Assigning values to variables

Name=jerry

Path: Paths separated by colons

0 (1)

Type: display specifies which type to belong to

Date: Time Management

Linux:rtc

Hardware clock

System clock

Get help with the use of commands:

Internal command:

Help COMMAND

External command:

COMMAND--help

Command manual: MANUXL

Mans COMMAND

Sub-chapters:

1: User command

2: System call

3: Library User

4: Special files (device files)

5: File Format (configuration file syntax)

6: Game

7: Miscellaneous (Miscellaneous)

8: Management Command (/sbin,/usr/sbin,/usr/local/sbin)

<>: Required

[]: Optional

... : multiple times can occur

|: Choose one More

{}: Grouping

Mans:

Name: command names and features brief description

Synopsis: Usage notes, including available options

DESCRIPTION: A detailed description of the command function, which may include the meaning of each option

Options: Explaining the meaning of each option

Files: The configuration file associated with this command

BUGS:

EXAMPLES: Using the example

See ALSO: Another reference

Flip Screen:

Turn back one screen: SPACE

Turn One screen forward: b

Turn back one line: ENTER

Turn One line forward: K

Find:

/keyword: Backwards

N: Next

N: Previous

？ KEYWORD: Forward

N: Next

N: Previous

Q: Exit

Online Documentation:

Info COMMAND

Document:/ust/share/doc

Google

Practice:

Use date to get the system's current year, month, day, hour, minute, second separately

Hwclock

-W: Write the system time into the hardware

-S: Writes the hardware time to the system time,

Cal:calendar

Practice:

1. is echo an internal command or an external command?

2, its role?

3, how to display "Tje year is 2013." Today is 26. " For two lines?

Escaping, escaping

Practice:

1. is printf an internal command or an external command?

2, its role?

3, how to display "The year is 2013." Today is 26. " For two lines?

The file command and its usage.

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Common commands for Linux operating systems