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linux install MySQL8.0.20
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I finally
installed MySQL8.0.20 according to linux
and successfully completed the MySQL installation.
During the installation process, service mysql startI encountered a problem in starting MySQL in the thirteenth step
. I forgot the specific error message, it seems to be like this

/etc/init.d/mysql: line 239: my_print_defaults: command not found
Starting MySQL ERROR! Couldn't find MySQL server (/usr/local/mysql/bin/mysqld_safe)

Solution:
①The my.cnf file in the tenth step needs to be created manually
The content is:

[mysqld]
basedir=/usr/local/mysql8.0.20/
datadir=/usr/local/mysql8.0.20/data/
socket=/tmp/mysql.sock
character-set-server=UTF8MB4
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd
 
#[mysqld_safe]
#log-error=/var/log/mariadb/mariadb.log
#pid-file=/var/run/mariadb/mariadb.pid
 
#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

At this point, this type of problem has been solved, but new problems will appear. In another article, there is an introduction to the transmission link
. After solving these two problems, you can successfully install

use mysql on linux

When using MySQL, you need to enter the bin in the MySQL installation directory to run ./mysql -u root -p, refer to → linux install MySQL8.0.28
insert image description here

Navicat can't create a database problem when stepping on the pit:

Navicat1044 cannot create database problem
View permissions:

mysql> SELECT host,user,Grant_priv,Super_priv FROM mysql.user;
+-----------+---------------+------------+------------+
| host      | user          | Grant_priv | Super_priv |
+-----------+---------------+------------+------------+
| localhost | root          | Y          | Y          |
| localhost | mysql.session | N          | Y          |
| localhost | mysql.sys     | N          | N          |
| %         | root          | N          | Y          |

UPDATE mysql.user SET Grant_priv='Y', Super_priv='Y' WHERE User='root';
FLUSH PRIVILEGES;

Or you can view the user authorization information: >show grants;or >show grants for 'username'@'%';
Solution: You need to authorize root@%:
grant all on exhibition.* to 'exhibition'@'%' identified by 'xxxxx' with grant option;
Finally, it is found that MySQL8 cannot create users and authorization at the same time | This method needs to be tried
. MySQL8 cannot use the above methods to authorize

own solution

Searching for a lot of tutorials on the Internet failed to solve the problem. Finally, I found that changing the create_priv in the user table to Y to
refresh the permission flush privileges;can create the database table. If it still cannot be created, just restart MySQL.
Change create_priv to Y

Withdraw authorization:

mysql> revoke all on *.* from 'username'@'%';

Navicat cannot create a database problem reference 1:1044 - Access denied for user 'root'@'%' to database 'exhibition'
Navicat cannot create a database problem reference 2
MySQL database revokes authorization

linux firewall

linux remote connection tool

Use rz, sz need to install related content
linux use rz, sz to upload and download files

Linux runs the jar package and inputs the log to a file

java -jar test.jar >test.log &

java -jar xx.jar >/dev/null 2>&1 &

The meaning of /dev/null 2>&1 &

scp command - upload and download files refer to 1
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