Reset MySQL root password in Linux

Stop mysqld service:

systemctl stop mysqld

Create a /pwd.txt file with following contents:

cat /pwd.txt 
ALTER USER 'root'@'localhost' IDENTIFIED BY 'pwd123';

be sure that the /pwd.txt will be accessible by mysql user.

Run mysql daemon with --init-file option:

mysqld --init-file=/pwd.txt &

Try to login:

mysql -u root -ppwd123

If login succeded kill mysqld running process and start the service:

killall mysqld #several times
systemctl start mysqld