Linux--date commands, directory-related commands

One, date order1. Date command

Command format:

date [OPTION] ... [+format] # Displays the current system time;

Show time format (date ' +%y,%m,%d,%h,%m,%s '):

format Formats	meaning
%y,%y	Years
%m	Month
%d	Day
%H	When
%M	Score of
%s	Seconds
%u	Weeks

date [MMDDHHMM[[CC]YY][.SS]] # Set system time

• MM: Monthly
• DD: what date
• HH: Hours
• MM: Minutes
• YY: two-digit year
• CCYY: four-bit year
• . SS: Seconds

Two types of clocks for Linux:

• System clock: The timing of the CPU's operating frequency by the Linux kernel;
• Hardware clock: hwclock: Display hardware clock

Options:

• -S,--hctosys # Set system time from hardware clock
• -W,--SYSTOHC # Set hardware clock from current system time

1 Exercise: Date command2 3 What is the day of the week? 4 #Date ' +%u '5 6 set the current system time? 7 #Date 111213142015.168Set time: November 12, 2015 Thursday 13:14:16CST9 TenShow today's date, shaped like: 08/15/15?  One #Date ' +%d ' A  -Displays the current time, shaped like: 16:01:21?  - #Date ' +%t '

View Code2. Cal Command

The Cal # command is used to view the current calendar,

Cal-y 2008 # View 2008 Year calendar

Ii. Directory-related commands

Main directory, home directory:

• Root:/root
• Normal User:/home/username
• User's home directory: ~

a.cd Command

Command	meaning
Cd	Switch to the current user's home directory (/home/user directory), when the user logs in, the default directory is the user's home directory.
CD ~	Switch to the current user's home directory (/home/user directory)
Cd.	Switch to current directory
Cd..	Switch to Parent directory
CD-	Access to the directory where you last came

b.pwd Command

Displays the current directory.

c.ls Command

Command format:ls [OPTION] ... [FILE] ...

Options:

• -A,--all: Displays all files, including hidden files;
• -L: Displaying file details in a list
• -H: Display file size in a humane way with-l
• -D: Displays the relevant properties of the directory itself, usually with-l;
• -R,--reverse: Reverse Display
• -R,--recursive: recursive display
• -ll <==>-alh

The meaning of the information in the picture:

d.cat Command

Print the contents of a file to the screen

Command format:cat [OPTION] ... [FILE] ...

Options:

• -E: Display line terminator $
• -N: Numbering each line displayed

e.file Command

View File types

Format:file/path/to/somewhere

third, System Management class command

1, Shutdown: Halt, Poweroff

2. Restart: reboot

• -F: Force, do not call shutdown
• -P: Power off

Shutdown

Instruction format:shutdown [OPTION] ... Time [MESSAGE]

Options:

• -r:reboot
• -h:halt
• -c:cancel

Set Time:

• Now: Immediately
• +m: The relative time representation, since how long after the order was submitted; for example +3;
• HH:MM: Absolute time, indicating the specific time;

3. User login Information View command:

• WHOAMI: Displays the current login valid user;
• Who: All current logon sessions of the system;
• W: all current login sessions and the operation of the system;

Linux--date commands, directory-related commands