To view

The command explain
ls View the files in the directory
ls -a View directory files (including hidden files)
ls -R a View all levels in the directory
ls -L a View details in directory A
pwd View the current directory
cat Text content is displayed to the terminal
head -5 a View the first 5 lines of file A, default 10 lines
tail -3 a Look at the end of file A 3 lines, default 10 lines
tail -f a Look at the A file, and do update tracking
wc -l a See how many lines are in file A
whoami View your user name

Create a directory

The command explain
mkdir a Create a directory named A
mkdir a b c Create directories A, B, and C
mkdir -p a/b/c Create a multi-level directory. In this example, directory C under directory B is created

delete

The command explain
rmdir a If you want to delete directory A, only an empty directory can be deleted
rm -rf a Delete a directory, non-empty directory can also be deleted, and no prompt, use with caution!

copy

The command explain
cp -r css-magic a/ Copy the entire csS-maigc directory to directory A
cp -r dir* .. / Copy all directories starting with dir to the directory at the previous level
cp -r dir? ../ Copy directories starting with dir + one character to the directory at the previous level
cp -p Retain file attributes such as user, permission, and time
cp -a Equivalent – dpR???

mobile

The command explain
mv a b Move or rename file A to b

Packaging and compression

The command explain
tar cf a.tar a Package a file
ls -lh a.tar View the size of a compressed file in units, for example, M/G
tar czf a.tar.gz a Package and compress the a file, where.tar.gz is a double extension to indicate that the file is compressed for readability, CZF c for package, Z for zip, and f for file operation type
tar cjf a.tar.bzip2 a Bzip2 compression is higher than Gzip but slower than Bzip2 compression
tar xzf a.tar.gz -C ./ Decompress the S package to the current directory. In XZF, x stands for unzip, z because the unzip is gzip, and f is a file

Text editing

The command explain
vi a Go inside file A
  • operation
Text editing operation instructions explain
hjkl Cursor position movement
yy Copy the entire line
3yy Copy 3 rows consecutively
y$ Copy from cursor position to end
p paste
d shear
5dd Represents a continuous cut of 5 lines
u Undo last operation, can be undone many times
ctrl + r Too many retractions. Pull back
x Delete the specified character
R + New character replace
:set nu According to the line Numbers
:set nonu Remove the line Numbers
/x To find the character x, press N (down), Shift + N (up) to move it up or down
:s/m/o Replace the m character with o on the line where the cursor is located
:%s/m/o/g All m characters found in the text are replaced with O
:set hlsearch Display search highlighting
:set nohlsearch Remove search highlighting
v Visual mode (single character)
shift + v Visual mode (row)
ctrl + v Visual mode (block)

Users and user groups

The command explain
Enter the password after sudo -i Temporarily switch to root to perform root permissions
su – a Switch to user A
exit Switch back to a common user from the root user
useradd a Create a user named A
id a Query for user A
passwd a Change user A’s password
userdel -r a Delete user A, if -r is not added, then the user’s home directory is not deleted
usermod Modifying User Information

The output

The command explain
echo Displays information on the terminal
echo 123 > a.log Print 123 to the a.log file

other

The command explain
cd Change the directory
touch Create a file

File directory

The path explain
/etc/passwd Store user files
/etc/shadow User password related files
chmod Example Modify file and directory permissions
chmod u+x readme.md Add execute permission to the user part of the readme.md file. U = user, + = add permission, x = execute permission (r: read, w: write, x: execute)
chmod g-r readme.md G-r: g stands for group, – stands for delete, r stands for read (r reads, W writes, x executes)
chmod o=w readme.md Add write permission to other user permissions of the readme.md file. O =w indicates other, = indicates one-time operations, such as deleting read permission and adding write permission. W indicates write permission (r read, W write, x execute).
chmod a+r readme.md Add read permission to all users, groups, and other users of the readme.md file. In a+ R, a stands for all, + stands for add, and r stands for read permission (r reads, W writes, and x executes).
chmod 111 readme.md Configure only execute permissions for readme.md file users and other users. 111: the first 1 represents user, the second 1 represents group, and the third 1 represents other users (1 performs 2 writes 4 reads).
chmod 777 readme.md Configure all permissions for the readme.md file user and other user groups. 7 represents 1+2+4 (1 performs 2 writes 4 reads).
chown Change the owner and owner group
chown a test Change the owner of the test file to user A. Chown is short for change owner and requires root permission 
/ / vim/etc/passwd file clsmall: x: 1001-1001: : / home/clsmall: / bin/shCopy the code

explain

  • Clsmall: user name
  • X: Whether password authentication is required
  • The first 1001: UID, which cannot be changed arbitrarily, will be programmed for that user if it is changed to an existing ID
  • Second 1001: Which group does the current user belong to
  • /home/clsmall: indicates the location of the home directory
  • /bin/sh: indicates the user command interpreter
  • There are two consecutive colons in it: :This is the position of the comment
// vim /etc/shadow clsmall:$6$jveUn92k1qeyIivH$YnBK/M8w6Tpj0.M0a4hRVX6GPjeN//4Klp2Qmbs5pV4Zv/nkVhhQUDBS00h5Gv7DUHe1w2laywUoASlFC0Lwj.:18795 : 0:9 9999:7: : :Copy the code

explain

  • Clsmall: indicates the user name
  • After a string: encrypted password, here even if the same password is set, encryption is not the same, in order to avoid the set out of the password
// vim /etc/group
root:x:0:
Copy the code

explain

  • Root: indicates the group name
  • X: Whether password authentication is required
  • 0: Gid is 0
Log is used as an example. -rwxrwxrwx 1 cl cl 44 Jun 11 15:35 publishCopy the code

explain

  • -Represents a common file
  • RWXRWXRWX: r stands for read, w stands for write, and x stands for execute. The first RWX represents the permissions of the file owner, the second RWX represents the permissions of the file owner group, and the third RWX represents the permissions of other users.
Drwxr-xr-x 1 cl cl 4.0K Jun 21 18:25 test drwxr-xr-x 1 cl cl 4.0K Jun 21 18:25 testCopy the code

explain

  • D: indicates a directory file. The owner has read and write permissions on the test directory, and the owner group and other users have read and execute permissions on the test directory

Special privileges

// /usr/bin/passwd The // s file indicates that the owner permission is obtained when the command is executed. Root -rwsr-xr-x 1 root root 67K May 28 2020 passwd //usr/bin/temp // t indicates that only root and the user who created the file can operate the file DRWXRWXRWT 1 root root 512 Jun 22 10:47 tmpCopy the code