###1. mysql command not found
reason: This is because the system will find the command under /usr/bin by default, if this command is not in this directory, of course, you will not find the command, all we need to do is map one Linking to the /usr/bin directory is equivalent to creating a link file.
First you need to know the full path of the mysql command or the mysqladmin command. For example, the path to mysql is: /usr/local/mysql/bin/mysql, we can execute the command like this:
ln -s /usr/local/mysql/bin/mysql /usr/bin
via whereis mysql To query the installation path of mysql, establish a mapping relationship.