How to get the use of commands under Linux Help

0, Linux commands are divided into:

Internal command: Command inside the shell

External command: A command stored in a file or script

How do I see whether a command is an internal or external command? A: Using the type command, use type commands

1. help get a brief information about the command

Internal command:

Helpcommand

External command:

Command–help

2. Command manual:manual Man Command

Man [12345678] COMMAND

2.1 chapters (meaning of each chapter):

how do I see which chapters each command appears in? A: Using the Whatis command, use whatis commands

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

Eg:man ls

2: System call

Eg:man 2 Read

Whatis Read

3: library user

A library call is a library call, a system call is a system call, but it is possible to have the same name.

A library is a function that cannot be executed alone and can be called only by other programs. No entry was executed.

4: Special files ( device files )

character devices: linear access

Block devices: Random access

Special files: No file content (i.e. data), only file attributes (i.e., data elements)

Eg:man 4 TTY

5: File format ( configuration file Syntax )

eg:cat/etc/passwd

whatispasswd

Man5 passwd

6: Game

7: Miscellaneous (Miscellaneous)

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

Eg:man Mount

The meaning of each of the 2.2 man in accordance with what is represented

1, <>: Must choose

2, []: Optional

3 、... : Multiple times can occur

4, | : Choose one More

5. {}: Grouping

2.3 Individual headings in the man document :

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

Seealso: Another reference

2.4 How to Flip the screen in the Help document:

Turn back one screen: SPACE

Turn One screen forward:b

Turn back one line: ENTER

Turn One line forward:K

2.5 How to find keywords in the Help document:

/keyword: backwards

N: Next

N: Previous

? KEYWORD: Forward

N: Next

N: Previous

Q: exit

3. Online Documentation: INFO COMMAND

4. Document:/usr/share/doc

Only by knowing how to look at each of the help documents can we learn to command and not start, so as to achieve the improvement of learning efficiency. Does not accumulate Kuibu not even thousands of miles, does not accumulate the small stream not to become the river. Learning is down-to-earth accumulation, is unswervingly to adhere to!

How to get the use of commands under Linux Help