Linux editor introduction

About text editors

There are many text editors, such as gedit, kwrite, OpenOffice in graphic mode, and editors in text mode include vi, vim (enhanced version of vi) and nano... vi and vim are our most commonly used editors in Linux. It is necessary for us to introduce the simplest usage of vi (vim) so that entry-level Linux users can learn to use it in the shortest time. The nano tool is similar to the edit operation under the DOS operating system and is easy to use. We will not introduce it here. If you are interested, you may wish to try it;

vi Editor

Why you need to learn to simply use vi vi or vim is the most basic text editing tool in Linux. Although vi or vim does not have the simple operation of clicking the mouse like a graphical interface editor, the vi editor plays an important role in system management and server management. , it can never be compared to an editor with a graphical interface. When you do not install the X-windows desktop environment or the desktop environment crashes, we still need the editor vi in ​​character mode; The vi or vim editor is the most efficient tool for creating and editing simple documents;

How to use vi editor

How to call vi

[root@localhost ~]# vi filename ~ ~ ~ ~ ~ ~ ~ ~ ~

vi’s three command modes

Command (command) mode, used to enter commands ; Insert mode, used to insert text; Visual mode, used to visually highlight and select text;

Save and exit files

Command mode is the default mode of vi or vim. If we are in other command modes, we must switch to it through the ESC key. When we press the ESC key and then enter the : sign, vi will wait for us to enter the command at the bottom of the screen;

:w Save;

:w filename Save as filename;

:wq! Save and exit;

wq! filename Note: Save and exit with filename as the file name;

q! Exit without saving;

:x should save and exit, the function is the same as :wq!

Cursor movement

When we press ESC to enter Command mode Finally, we can use the following keys to move the cursor; j moves one line down; k moves one line up;

h moves one character to the left; l moves right Move one character;

ctrl+b moves up one screen; ctrl+f moves down one screen;

Up arrow moves up; Down arrow moves down; left The arrow moves to the left; the right arrow moves to the right; When we edit a file, for the j, k, l and h keys, we can also add numbers in front of these action commands, such as 3j, which means move down 3 lines.

Insertion mode (text insertion)

i inserts before the cursor; a inserts after the cursor;

I at the cursor location Insert at the beginning of the line; A Insert at the end of the line where the cursor is;

o Insert a line below the line where the cursor is; O Insert above the line where the cursor is One line;

s Delete a character at the cursor position, and then enter insert mode; S Delete the line where the cursor is, and then enter insert mode;

Deletion operation of text content

x One character; #x Delete several characters, # represents a number, such as 3x;

dw deletes one word; #dw deletes several words, # is represented by numbers, such as 3dw means deleting three words;

## dd deletes one line; #dd deletes multiple lines, # represents a number, such as 3dd means to delete the cursor line and the next two lines under the cursor;

d$ Delete the content from the cursor to the end of the line;

J Clear the space between the line where the cursor is and the previous line, and connect the cursor line and the previous line together;

Restore modification and delete operations

u Undo the modification or deletion operation; press the ESC key to return to Command mode, and then press the u key to undelete the previous deletion or modification; if you want to undo multiple previous modifications or deletions To operate, please press u several times. This is not much different from the undo operation of Word;

Visual mode

In the latest Linux distribution, vi provides Visual mode, because this function is only available in vim. If the vi you are using does not have this function, just replace it with vim. Turn on the visual mode, press the ESC key, and then press v to enter the visual mode; the visual mode provides us with an extremely friendly selection of text range to highlight; it is displayed at the bottom of the screen; --Visual- -

or

--VISUAL--

Enter the visual mode, we can use the above mentioned The cursor movement command in command line mode can select a text range. What is the use of selecting a text range? We can delete a certain part of the assignment and press the d key to delete the selected content. After selecting the content, we press y to copy; press d to delete; it is worth mentioning that deleting also means copying. We return to the command mode, then move the cursor to a certain position, and then press the shift+p key to paste the content we just deleted. Let’s mention it here first, and we’ll have to talk about it in detail later. To exit visual mode, still use the ESC key;

Copy and paste operations

In fact, deletion also means cutting. When we delete text, we can move the cursor somewhere and press shift+p Press the key to paste the content in place, then move the cursor somewhere, and then press p or shift+p to paste again; p pastes after the cursor; shift+p pastes before the cursor. Here is an example. : For example, we want to copy the third line of a document and paste it after the fifth line. What should we do? There are two methods; the first method: first delete the third line, move the cursor to the third line, then use the dd action, and then press the shift+p key. This will put the third line you just deleted in its original place. Then we use the k key to move the cursor to the fifth line, and then press the p key again, so that the content of the third line is pasted to the back of the fifth line; Second method; Enter visual mode, press the ESC key, Then press the v key. Move the mouse pointer, select the content of the third line, and then press the y key to copy; then move the pointer to the fifth line, and finally press the p key; Therefore, the copy and paste operations are a comprehensive use of command mode, insert mode, and visual mode; we To learn to switch between various modes, use the ESC key frequently; more importantly, learn to move the cursor in command mode;

About line numbers

Sometimes when we configure a program to run, an error occurs in line X of the configuration file. At this time we need to use line number related operations;

Add line numbers to all content; Press the ESC key, and then enter:

set nu

set nonu Cancel the line No.

n Jump to line n

Find and replace function

Find

First, We need to enter the ESC key to enter the command mode; we enter / or ? to enter the search mode;

：/SEARCH Note: To search SEARCH forward, press the n key to move the cursor to the next qualified place ;

: ?SEARCH Note: To search SEARCH in reverse, press the n key and move the cursor to the next qualified

For example: For example, I want to find the swap word in a file, What I should do is as follows; First press the ESC key to enter command mode, then enter: /swap or ?swap

to replace

Press the ESC key to enter command mode;

: s /SEARCH/REPLACE Note: Change the ## in the line where the current cursor is located #The first SEARCH word, replace it with REPLACE

:s /SEARCH/REPLACE/g Note: Replace the SEARCH word in the line where the cursor is currently with REPLACE , and highlight all SEARCH;

%s /SEARCH/REPLACE Note: Replace the first SEARCH of all lines in the document with REPLACE;

%s /SEARCH /REPLACE/g Note: Replace all SEARCH in the document with REPLACE;

:#,# s /SEARCH/REPLACE/g Note: # represents a number, indicating from how many lines to how many lines, replace SEARCH Replace with REPLACE; Note: Among them, g represents global search; we noticed that SEARCH will be highlighted even if there is no replacement;

Example: For example, we have a document to be modified; we replace all the words the with THE in the line where the cursor is located, it should be :s /the/THE/g
We replace all the words in the entire document Replace the with THE, it should be :%s /the/THE/g
We just replace the in lines 1 to 10 with THE, it should be :1,10 s /the/THE/g

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