22/02/14 study notes

Xshell operation

One 、 First line analysis ：

• hadoop： user name
• @node100： Host name
• ~： Home directory

Two 、 Some basic commands

ls： Displays the directory under the current directory （ file ） Information

ll： Displays the directory under the current directory in detail （ file ） Information

cd ：
cd Directory name ： Enter the corresponding directory
cd .： Current directory
cd … ： Return to the previous directory
cd / ： Go to the root directory
Table key ： Automatic completion
Up key ： Call the last code （ You can press... Many times ）
Down key ： Used in conjunction with the up key

pwd： Displays the current file or directory as an absolute path

3、 ... and 、 Absolute path and relative path

Absolute path ： The directory name string from the root directory to the target directory , Intermediate use / Connect
eg： There are... In the root directory dev Catalog ,dev Under the directory block Catalog , Use absolute path to access block Catalog ;

Relative paths ： Directory name string from its own directory to the target directory , Intermediate use / Connect
eg：

Four 、Linux Addition, deletion and modification of

1. Add Directory

Prerequisite ： Confirm to create a new directory under the target directory
eg： stay ~ New under the directory test Catalog ：
Instructions ：mkdir test

odd file
eg： stay ~ New under the directory testfile file
Instructions ：touch testfile

2.VI Editor

vi The editor can edit the file ,vi Fit to CentOS 7;
Instructions ：vi testfile

Enter the appeal order to enter the order mode , In command mode , Press i、a、o You can enter the insert mode by pressing the key , Then you can edit what you want to input in the file , Press esc Key to exit command mode , Press... In command mode ： You can adjust to the bottom line mode , In bottom line mode ‘q’ The command is to exit without saving , Press ‘wq’ Is to save and exit ,q Add a ‘！’ On behalf of forced exit ;

About vi For some specific operations in the editor, please refer to the following elder's article ：
vi/vim Getting started with the editor

Check the contents of the file
Instructions ：cat file name
eg:cat testfile

Copy of documents
Instructions ：cp The original path The target path
eg：

 cp ./testfile /opt

File movement
Instructions ：mv The original path The target path
eg：

mv ./testmv /opt`

Delete
Prerequisite ： You must have permission to successfully delete
eg： Delete file

eg： Delete directory

rm -rf testrm

Linux man Command Introduction

man rm

Find file command
Instructions ：find

3. File content query

（1） Output all the contents of the file

cat： Positive sequence output
tac： Output in reverse order

• Be careful ：cat And tac Output in reverse order is in reverse order by line , So for a file with only one row of data cat And tac It is equivalent. ;

（2） Press line to output

head -n Digital parameters Target file ： Output the content corresponding to the number of lines in front
tail -n Digital parameters Target file ： Output the content of the number of lines corresponding to the next starting number


In the above figure, three lines are output because there is another line at the end of the figure that is also included ;

• Be careful ： Empty lines are included , When there is a blank line, it will be counted , Pay particular attention to the blank lines at the end

（3） Range queries

sed -n ‘ The first few lines begin , Which line ends p’ Target file

（4） When viewing content , At the same time, it shows the percentage function of the place you read

more File name
eg;

more /etc/profile

You can read down by entering ;

（5） You can use the up and down keys to adjust the reading position when viewing the content

less File name
eg：

less /etc/profile

You can use the up and down keys to adjust the reading position according to your reading needs ;

• notes ：more And less Commands can be obtained by pressing q Skip reading ;