Check if MySQL User Exists on Command Line (and in Puppet)

If you are using Linux, there is simple way to check if a user exists in MySQL:

echo `mysql -u root -p**[your root password]** -e 'use mysql; SELECT user FROM user;'` | grep '[user name]'

Executing this command will exit with return code 0 if the user exists and otherwise exit with 1.

This is very useful for building puppet scripts. The following execution will create a user if it doesn't exist.

exec { "add user if not exist":

unless => "echo `mysql -u root -p**[psw]** -e 'use mysql; SELECT user FROM user;'` | grep '[username]'", path => ["/bin", "/usr/bin"], command => "mysql -u root -p$mysql_password -e \"**[Create User/Grant Rights Here]**\"", require => Service["mysqld"], }