02-02-linux operating system and common commands

Date: Time Management

LINUX:RTC (Hardware time), read hardware time via RTC

Hardware time Clock or hwclock;hwclock-w: Synchronizes the system time to hardware time; Hwclock-s: Synchronizes hardware time to system time

System Time Clock

NTP: Network Time Protocol

Get help with the use of commands:

Internal command:

Help command

External command:

Command--help get brief command Help

Command manual: Manual

Mans command

Sub-chapters: General 8 Chapters, Whatis command: Shows which chapters a command appears in

1: User commands man 1 command

2: System calls Man 2 command

3: Library user man 3 command

4: Special files (device files) Man 4 command

5: File format (config file syntax) Man 4 command

6: Game

7: Miscellaneous: Miscellaneous

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

<>: Parameters that must occur

[]: Selectable parameters

... : Can appear multiple times

|: Choose one More

{}: Grouping

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 screen: enter

Turn One screen forward: K

Find:

/keyword: Backwards

N: Next

N: Previous

？ KEYWORD: Forward

N: Next

N: Previous

Q: Exit

Info command: View command online Help

Help documentation also exists in the/usr/share/doc directory

Google Help

Official website

Cal: Calendar

Cal: Show Calendar

Cal year: Show calendar for a year

Cal Month Year: Displays a calendar for the month of the year

Practice:

echo is internal or external command

Its role

How to display "The year was 2013.today is 26." is two lines

Whether printf is an internal or external command

Its role

File command and its usage

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02-02-linux operating system and common commands