Rookie Learn Linux NO. 004 notes Linux time and help command

First, time management date

Date: Displays the current time to view the system time

Date Mmddhhmmyy. The SS modifies the current system time by the month of the year. seconds

Date +format Displays the time date in the format

+%d display date;

+%y display year;

+%s display second;

+%m display minute;

+%n a newline;

+%m month;

Hwclock: Hardware Time hwclock-query and set the hardware clock (RTC)

- W synchronizes system time to hardware time

- s saves hardware time to the system time

Clock: hardware Time

The operating system acquisition time is obtained from the computer hardware clock and then set to the system time

NTP (Network Time Protocol), the operating system can set a time server to get the current time

Linux RTC (Real Time Clock)

Linux has two clocks

Time on hardware clock hardware

System clock Linux system own time timer

Caldisplays a calendar

Export lang=en Adjust Character set

Ii. access to commands help

1. Internal command:

Help COMMAND

2. External command:

Command--help (most external command support)

3. Command manual: Manual (commonly used to view external command manuals)

Man command (used to view command manuals)

The Whatis command is used to display brief information about commands, which can show which chapters of a command

Man display Help section of 8 common

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

2: System call

3: library Call

4: Special documents (equipment files, etc.)

5: File Format (configuration file syntax)

6: Game

7: Miscellaneous

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

Man manual format

Name names

Synopsis Overview, Summary, overview

<>: Required

[]: Optional

...: can occur multiple times

| Choose one More

{} grouping

DESCRIPTION Description

Options option

Files file

BUGS Error

EXAMPLES Example

AUTHOR Author

See ALSO additional references

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

Example:/time

N: Next

N: Previous

? Keyword: Forward

Q: Exit

4. Online Documentation:

Info COMMAND

e.g Info Mans

Info HWCLOCL

5.document:

/usr/share/document can view documentation manuals

6.google

7. Check its official site

Little Practice

1.echo is an internal command or an external command?

Type echo

2. How does it work?

Mans Echo

3. How to display "The year is 2016." Today is 26. "For two lines?"

Echo-e "The year was 2016.\ntoday is 26."

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Rookie Learn Linux NO. 004 notes Linux time and help command