Quando tento instalar o mysql-server, recebo o seguinte erro:
Reading package lists... Done
Building dependency tree
Reading state information... Done
mysql-server is already the newest version (5.7.20-0ubuntu0.17.04.1).
0 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
2 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up mysql-server-5.7 (5.7.20-0ubuntu0.17.04.1) ...
invoke-rc.d: policy-rc.d denied execution of stop.
update-alternatives: error: alternative path /etc/mysql/mysql.cnf doesn't exist
dpkg: error processing package mysql-server-5.7 (--configure):
subprocess installed post-installation script returned error exit status 2
dpkg: dependency problems prevent configuration of mysql-server:
mysql-server depends on mysql-server-5.7; however:
Package mysql-server-5.7 is not configured yet.
dpkg: error processing package mysql-server (--configure):
dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
Errors were encountered while processing:
mysql-server-5.7
mysql-server
E: Sub-process /usr/bin/dpkg returned an error code (1)
Parece que já está instalado, mas falhou durante o processo. Tente remover todas as instalações anteriores digitando
apt purge mysql-server
e se necessário
apt purge mysql-server-5.7
e tente novamente a instalação digitando
apt install mysql-server
(que é um meta pacote btw, ele irá instalar a versão mais recente do MySQL Server)