Getting Started with Linux (iii)

Linux Common commands:

Linux File system:

1. File names are strictly case sensitive

2. Files can use any character except/unexpectedly; special characters are not recommended

3. File name cannot be longer than 255 characters

4. Files with a. Start as hidden files

Working directory: Working directory

Home directory: Home

Common commands:

PWD: View current path, printing working directory

Show working directory

1.CD ~ Back to home directory//admin can switch to other people's home directory at will

CD ~username

CD-//Switch to previous directory

Echo $PWD

echo $OLDPWD//toggle between two variables

2.ls

-A: Show all files, including hidden files

-A: Displays except. and. All files except the

-l:--long long format, long format list, which displays detailed property information for a file:

-rw-r--r--. 1 root root 89458 October 14

rw-r--r--

rw-: File owner's permissions:

r--: Permissions for file groups

r--: Permissions for other users

1: Number of times a file has been hard linked

Root: The owner of the file

Root: The genus Group of the file

89458: Size of file, Unit is byte

-h:--human-readable: The file's

-d:--directory//Display the properties of a directory

-R: Reverse display,

-R: Recursive display, contents of subdirectories under Directory

3.cat; concatenate

File Text Viewing tool

Cat/etc/fstab

-N Display Line number

-e Display line terminator $, not very useful

4.tac text File View

Reverse View//First line, change to last line

5.file

Determine the file type:

File//View files Content type:

File

6.echo

-N No Line break

-e escape character in effect

Echo-e "Hello \nworld"

echo OPTIONS "STRING"

' Echo ' interprets the following backslash-escaped characters:

\aalert (Bell)

\bbackspace//delete the previous character

\csuppres s further output

\eEscape character

\fForm Feed

\n New Line newline character

\R carriage return

\t horizontal tab Horizontal tab

\vVertical tab Vertical tab

STRING:

Single quote: Strong reference, variable reference does not perform substitution

Double reference: Weak application, variable reference will be replaced

The escape character can be referenced in ""

7.shutdown

Shutdown OPTIONS time [WALL]

-H

-P

-R

-K warning, but no shutdown

-H time

12:00//

Now + 3min

+3//Three minutes later

-C Cancel Shutdown

Wall "Wolf"//Send broadcast message to all users logged in to the host

Shutdown-r +5//5min After shutdown, will prompt everyone

Shutdown-c//Cancel, will also notify everyone

Shutdown-r +5 "Hello everyone"//shutdown with prompt information

8. Date

1.date

Date [OPTION] ... [+format]//Specify display format

Date [-u|--utc|--universal] [MMDDHHMM[[CC]YY][.SS]]//Set time

The year can be two-bit, and four-bit, seconds.

Date +%f-%t

2017-01-10-13:06:47

Date "+%f%T"//

2017-01-10 17:40:15

Date +%y-%m-%d-%h-%m-%s

Month and day time

Date +s//1970.1.1 00:00 to present number of seconds, Unix system start and end time

Date +%j//The day ordinal of a year

2.clock//hardware clock, coin cell

Hwclock//Links only

-S,--hctosys//HC write to Sys

-W,--SYSTOHC//sys write to HC

3.cal

cal-j 02 2017//02 Month for the first day of the year

Aa.

Linux: The date and time information is read from the hardware when the system starts, and is no longer associated with the hardware after the read is completed

Date: System clock

Clock: Hardware Clocks

9. Homework:

which//view the full path of the command

Whereis//Command binary file path, source path, manual path

-B Binary File path

-M manual Path

-S Source Path

Whatis//often see man help documentation, there are several public

W.H.O.

-B Boot Time

-H user when logged in, from which IP landed

-R Current Run level

W Several users log in, what are they doing

-H do not display headers

Summary:

1. Components of the program 4: binary files, library files, Help files, configuration files

2.ls,cat,echo

3.date, Hwclock

Getting Started with Linux (iii)