Rhcsa day 3

1、 Sum up vim Of the three modes, the commands you think are practical

1、Vi/vim  (-o)   file 1   file 2（ Open two files ）ctrl+w+w Switch

Command mode ：

d Delete ,dd Deletes the line where the cursor is located x Delete cursor u withdraw

G Jump to the end （ Numbers G Jump to line number ）  ^ Head of line   $ At the end of the line

( Numbers )yy Copy line ( Numbers )cc shear p Paste

Last row mode ：

Wq!( preservation 、 sign out 、 mandatory ) nu\nonu( Digital marker line exit )

r( Open the specified file to the next line )  noh( set nohlsearch )

%s /// Change the specified text

2、 File management command exercise ：

stay /opt Create a temporary directory under the directory tmp;
Create a file in the temporary directory , The file named a.txt;
take a.txt Copy it into b.txt; take b.txt Change its name to c.txt;
Create symbolic links , The linked file name is linkc.txt;

[[email protected] ~]# mkdir /opt/tmp
[[email protected] ~]# cd /opt/tmp
[[email protected] tmp]# touch a.txt
[[email protected] tmp]# cp -p a.txt b.txt
[[email protected] tmp]# mv b.txt c.txt
[[email protected] tmp]# ln -s c.txt linkc.txt

3、vi practice ： Complete the following steps
1) application vi Command in /tmp Create files under folders , file name newfile. stay newfile Enter the date and time on the first line

2) take /boot/grub2/grub.cfg The contents of the document are read into newfile In the document （ On the next line of the date, i.e 2 That's ok ）
3) Find documents that contain # The line of the sign character , Delete entire line

4) Turn on VI Line number prompt function

：set nu        // Turn on the line number prompt 
：set nonu      // Turn off line number prompt 

5) Move the cursor to 5 That's ok , And in the first place 5 A new blank line is generated after the line 6 That's ok

 Can be in command mode yy( Copy ） A blank line again p( Paste )
 Or in input mode   Enter key 

6) Modify the content . Will all timeout=5, Change to time=30

：%s/timeout=5/time=30

7) All... In the entire document root The character is changed to admin character

：%s/root/admin

8) Copy No 1 The date and time content of the line to the end of the document

 Can be in command mode yy( Copy ） The first line again p( Paste )
 In command mode         gg Move to first line         G Move to last line 

9） Save the document , Save the document again as /boot/newfile2, sign out VI Editor  

4、 The file to view

Copy user profile to /opt Under the table of contents ;
see /opt/mima File first 6 That's ok ;

5. Statistics show user profiles nologin Number of occurrences

6. Displays the total number of users in the system
7. Set the system time （ Minutes and seconds ） write in time file
8.history The system command history can be displayed , Count the top three with the highest command frequency of the current system .（ The command repeats three more commands ）