Get Linux command Help

First, help Command
Applies to internal commands
Example:

Copy Code

The code is as follows:

# Type cd
CD is a shell builtin
# Help CD
# type LS
LS is aliased to ' LS--color=auto '
# Help LS
-bash:help:no Help topics match ' ls '. Try ' help ' or ' man-k ls ' or ' info ls '.

Second, command–help/-h
Applies to external commands
For example:

Copy Code

The code is as follows:

# ls--help

Third, man Command

Example:

Copy Code

The code is as follows:

# Man CD

Note Manual manual is divided into chapters; Man # Command (#表示章节号)

Generation No.	Representative contents
1	Instructions or executables that the consumer can manipulate in the shell
2	The system core can call functions and tools, etc.
3	Some common functions and function libraries (library), most of which are C's function libraries (LIBC)
4	Description of the device file, usually in/dev file
5	The format of a profile or some file
6	Game (games)
7	Conventions and agreements, such as Linux file systems, network protocols, ASCII code, and so forth
8	Management instructions available to the system administrator
9	Documents related to Kernel

1, standard commands (command)

2. System calls (Systems call)

3. Library functions (Libraries function)

4, special devices (equipment description)

5. File formats (document format)

6. Games and toys (game and entertainment)

7. Miscellaneous (Miscellaneous)

8, Administrative Commands (Administrator command)

9 Other (Linux-specific) documents used to store kernel routines.

N new documents, you may want to move to a more appropriate area.

o old documents may be retained for a period of time.

L Local documentation, related to this particular system.

The man Command query operation references the command pattern in vi,vim usage

Read the man command syntax
[]: Optional content
<>: Must give the content
A|b|c: Choose one More
... : You can have multiple

Iv. Info Command
There are hyperlinks to stabilize the document, info is the information page, provide the author, version, when the release of more detailed information, man manual is to tell you how to use

Five, the README
Most programs have a corresponding help document, saved in the/usr/share/doc folder
Such as:

# ls/usr/share/doc/ntp-4.2.4p8/
ChangeLog COPYRIGHT NEWS

This format:

COMMAND Options Arguments

Specific Description:

Command: Represents the name of the commands, such as LS

Options: Defines the execution characteristics of a command and can have two options:

Long options: Use--boot, followed by complete words, such as--help

Short options: With-boot, followed by a single character, such as-a

Multiple short options can be used in combination, for example:

-h-l-A = =-hla

However, long options can not be combined, such as--help can not be followed by another word.

Options can also have their own parameters, note that between option and option, between options and parameters, there must be spaces between parameters and Parameters!

Arguments: Represents the Action object of the command, as in the above example,/etc is the object of the LS command.

In Linux, the symbols used for the options and parameters of the command also have a corresponding meaning:

[]: Can omit the content, optional

<>: Must provide

A|b: Two choose one, or choose one more

...: The preceding content can be repeated multiple times

{}: Grouping

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Get Linux command Help