1.3-linux basic Commands

Basic command:

Date

Date [Options] ... [+ format]: Time display

%d

%F

%T

Date [MMDDHHMM[[CC]YY][.SS]]: Time setting

MM: Month

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 time

--s,hctosys

--w,systohc

Directory-related commands:

Current directory or working directory

Home directory: Home

Root:/root

Normal User:/home/username

~: User's home directory

Cd:

CD or CD ~: Back to the current user's home directory

CD ~username: Switch to the home directory of the specified user

CD-: Switch back and forth between the previous directory and the current directory

Related environment variables:

PWD: The current directory path is saved

OLDPWD: The directory path where the last time was saved

PWD: Show current directory

Ls:list

Displays a list of files under the specified path

ls [options] ... [File] ...

-A,--all: show all files, including hidden files

-L: Long format

Ls-l Install.log//See first character (file type)

-rw-r--r--1 root root 38502 October 05:50 Install.log

- Normal files (text files, binaries, compressed files, movies, pictures ...) ）

D catalog file ( Blue )

b device file (block device) storage device hard disk, USB drive

C device file (character device) printer, terminal/dev/tty1

s socket file

P Pipeline file

L link file ( light blue )

9 bits in the back: access rights, Perm

1: Number of times a file has been hard linked

Left Root: Owner of File

Right root: Group of files

38502: Size of File

October 12 05:50: Last modified time of the file

Install.log: File name

-H,--human-readable: unit conversion

-D: Displays the relevant properties of the directory itself and is typically used with-l

-R,--Reverse: Reverse Display

-R: Recursive display

Stat/path/to/somefile: Gets the metadata for the specified file

File View command: CAT,TAC

Cat [OPTION] ... [FILE] ...

-E: Display line terminator $

-N: Numbering each line displayed

File type view commands:

File/path/to/somewhere

Echoing command: Echo

-N: Prevent automatic addition of newline symbols

-e: Allow escape characters to be used

\ n: Line break

\ t: Tab

echo "$VAR _name": Variables are replaced, double quotes indicate weak references

Echo ' $VAR _name ': variable does not replace, strong reference

Which: Displays the program file path for the command

which [options] COMMAND

--skip-alias: Prohibit alias use

Whatis

Use the Mkwhatis command to create a database of all help manuals and their corresponding keywords on the current system

1.3-linux basic Commands