mysql startup failure problem and scenario analysis

# Find the MySQL configuration file and copy the MySQL data directory vim /etc/my.cnf

# Enter the msyql data directory cd /data/mysql

# View the log file vim mysql.err

find / -iname "auto.cnf"

vim /data/mysql/auto.cnf

# Original content [auto]
server-uuid=64cbb3d1-e150-11eb-81a2-000c2972fe1f

# After adjustment, you can customize the content and replace the last digit f with a
[auto]
server-uuid=64cbb3d1-e150-11eb-81a2-000c2972fe1a


# Restart mysql
# centos7.x
systemctl restart mysql

# centos6.x
service myqld restart

cd /data/mysql
ll

# Find my.cnf
find / -iname "my.cnf"

# View the file content cat /etc/my.cnf

# Find this line of the my.cnf file socket=/tmp/mysql.sock

# Go to /tmp/
cd /tmp/

# View the contents of the file cat mysql.sock.lock 

# The number 9136 in the mysql.sock.lock file is the pid of mysql's operation
# Create mysql.pid in the root directory of mysql
vim mysql.pid

# Add 9136 in the mysql.sock.lock file just now # Restart mysql
systemctl restart mysql

# View mysql status systemctl status mysql

# Find my.cnf
find / -iname "my.cnf"

# View the file content cat /etc/my.cnf

# Find this line of the my.cnf file socket=/tmp/mysql.sock

# Go to /tmp/
cd /tmp/

# View the contents of the file vim mysql.sock.lock

# Add a pid that is not used in the current system. If you don't know how to check it, just randomly add a 4-digit number. For example, 9137

# Create mysql.pid in the root directory of mysql
vim mysql.pid

# Add 0137 in the mysql.sock.lock file to the mysql.pid file. Just keep it consistent. # Restart mysql
systemctl restart mysql

# View mysql status systemctl status mysql