"Original" Linux get commands for help with common commands

The shell command in Linux is usually the execution step: the user enters the command in the terminal, the system kernel reads the value of the environment variable in the current user's environment variable path The value of the variable is the path of the command, the command path is more than one, The system then matches the command file to find from left to right in these paths until it is found and executed, and when the command is executed, the file path corresponding to the command is saved in the hash table of the system so that the next time the user executes the command, a faster lookup is made to see the current user's hash table. You can perform a system built-in command hash to display the current user's hash table.
We use which to get the path of the command, use the type to determine whether the command is built-in command appears built-in command only built-in commands to get help
Help on how to view commands under Linux
1. The built-in commands are obtained by the Help command in the following format: help+ command
2, external command to get command help there are three ways: 1. Command +--help 2.man+ command 3, get online Help documentation via info.

A description of the paragraph in the document printed by the man command:

Name: A brief instruction, a description of the data name;

Synopsis: Brief Introduction to instruction release syntax (syntax);

DESCRIPTION: a more complete description;

Options: For the synopsis section, there is an enumeration of all available option descriptions;

COMMANDS: When the program (software) is executed, the instructions can be issued in this program (software);

Files: Certain files used or referenced or linked to by this program or data;

See ALSO: Can be consulted, with the instructions or data related to other instructions;

EXAMPLE: Some examples that can be consulted;

BUGS: Whether there is a related vulnerability;

Generally look at example, and then look at options can, if not solve the problem, and then see ALSO.
[]: Optional part;

{a|b}: grouping, A and B are used as a unit of use;

|: Alternatively, only one can be selected;

<>: There must be few parts;

... : Similar content can appear multiple;



Common commands:
1.CD Command: Switch directories
2 ls command: View files and directories, list means:
3. grep command: Commonly used to analyze a row of information
4. Find command: Very powerful command based on find
5. CP Command: Copy files
6, MV Command: Move directory, when the last parameter is the file is to represent the renaming
7. RM command: Delete directory of files
8. PS command
9. Kill command
10. File command: This command is used to determine the basic data of a file that is connected to the files command. The file types under Linux are not distinguished by prefix names
11. Tar command: Package common parameters for files:
-C: New package file
-T: See what file names are included in the contents of the packaged files
-X: Unpacking or decompression function, can be used with-C (uppercase) to specify the extracted directory, note-c,-t,-x cannot appear in the same command
-J: Compression/decompression via BZIP2 support
-Z: Compression/decompression with GZIP support
-V: Displays the file name being processed during the compression/decompression process
-F filename:filename for files to be processed
-C dir: Specify a directory for compression/decompression dir
12, Cat command: View the contents of the file more than more and less use
13, Chgrp: Used to change the file belongs to the group
14. Chown command: Change the file owner
15. chmod Command: Change file permissions
16. Time command how long to test a command.

"Original" Linux get commands for help with common commands