Rhcsa third day operation

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

 

 

 

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;

1. First create in the home directory opt as well as tmp Catalog

command ---mkdir

Command format ：mkdir -p /opt/tmp

-p——  You can quickly create each directory specified in the directory structure , Existing directories will not be overwritten

2. stay tmp Created in a.txt file  

command --cd   Toggle directory
command --touch       Create an empty file or update the modification date of an existing file or directory
Format ： touch  a.txt
If the specified file or directory already exists , Change the date and time of the file or directory to the date and time of the current system .
If the specified file does not exist , Creates an empty file with the specified file name

 3. take a.txt Copy into b.txt

command --cp         Copy (copy)  File or directory

command ： cp [  Options  ]  Source file   Target file

 

 

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

Enter in command line mode "/g/ The goal is /d", All targets in the document can be deleted

4) Turn on VI Line number prompt function

Input in command line mode "set nu" Line number can be displayed

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

Enter a number in command line mode and press enter to jump to the specified number of lines , And then in vi Press in mode "o" You can insert a new line under the cursor

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

Input in command line mode "/" You can find the input after the slash , For modification, add "%s", Pictured （%s Delete ten by default ）

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

Add at the back "/g" It means to process all the contents in the document

8) Copy No 1 The date and time content of the line to the end of the document
First in vi Jump to the first line in mode "gg", Copy "yy" Then jump to the last line "G" Then paste "p

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

In command mode "w" For preservation ,"w /（ The target path ）" Save as ,"q" To quit

 

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

cat /etc/passwd

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 ）

[[email protected]_server workspace]# last |awk -F " " '{ print $3 }' |sort -n |uniq -c |sort -nr |head -3