Linux Learning Notes < a >--common command

CLI (command line Interface) in the format:

Command option Parameters

Command Options ... arguments

Options: Short options:-character multiple options can be combined, such as-a-b=-ab

Long option:--word

Parameters: The Action object of the command

Control type:

Via Virtual terminal: CTRL+ALT+F1-F6

Through the terminal emulator: Click on the Open terminal in the GUI

Remote access via telnet or SSH

GUI (graphical User Interface) and CLI (Command line Interface)

Gui:x-window under the GNOME,KDE,XFCE, etc.

CLI:SH,BASH,CSH,KSH,TCSH,ZSH, etc.

Common commands:

1.su:switch User

Format: su [-l] Username

-L: Switch between user and shell environment

2.ls:list

Format: LS [-HAADIRR] Directory

-L: Display as long format

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File type: the

-: Normal file (f)

D: Catalog file (diretory)

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 permissions: 9-bit, every 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): units are bytes

Timestamp (timestamp): Modify time is displayed

Accessing access: Tools such as Cat view

Modify Modify: Content modification

Change changes: Change file properties

-H: Do unit conversions, display the file size bar in kilobytes

-A: Show multiple hidden files with. The current directory is represented: Represents the parent directory

-A: Displays hidden files that begin with. But not displayed. and.

-D: Display the directory's own properties

-I: Multiple display of the Index node column

-R: Reverse Display

-R: Recursive display

3.cd:change Directory

Format: CD: Home directory

~username: Enter the home directory of the specified user

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

4.hash: History command executes the cache of the path and logs the number of times, and next time do not check the path variable

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Environment variables:

Permanent: variable is permanently in effect and needs to be modified/etc/profile configuration file

Temporary: Variables expire when the shell is closed and declared with the Export command

Path: a bunch of paths separated by colons, the first time a command executes to find a path in path that holds the execution file of the command

PATH declaration format: path= $PATH: <path1>:<path2>, .....

5.type: Shows which type the specified command belongs to

Format: Type command

Command type:

Built-in commands (shell built-in)

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

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6.date: Manage system time, view and modify system time

Format: Date: Displays the current system time

Date-s mm/dd/yyyy: Revised month day

Date-s hh:mm:ss: Seconds and minutes when modified

Format:%y represents the year

%m represents the Month

%d = Day

When%h represents

%M represents the Division

%s = seconds

%s represents the number of seconds from 1970/01/01 00:00:00 UTC to Now

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7.hwclock: Manage Hardware time

Format: hwclock-w: Write system time to hardware time

-S: Save hardware time to System time

8.cal:calendar

Format: Cal: Displays the current month's calendar

Cal-3: Show calendar for this month and two months before and after

CAL-Y: Show this year's calendar

9. Get the use of commands to help:

Internal command:

Help command

External command:

Command--help

Command manual: Manual

Man command (typically used for external commands, used to display the user manual of the shell corresponding to the built-in command)

Man Chapter Command

Chapter:

1: User command (/bin,/usr/bin,/usr/local/bin)

2: System call

3: library file

4: Special files (device files)

5: File Format (configuration file syntax): For example, ETC/PASSWD file format

6: Game

7. Miscellaneous (Miscellaneous)

8: admin command (/sbin,/usr/sbin,/usr/local/sbin) administrator has permission to use commands

Special characters that appear in man:

<>: Required

[]: Optional

...: can occur multiple times

|: Choose one More

{}: Description of the sections in the group man:

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

Actions in Man:

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

Exit: Q

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Linux Learning Notes < a >--common command