Recover mysql/postgresql root password

To recover MySQL password you simply need to 

1) shutdown mysql database if it's possible or just kill with TERM 

In Linux :

# service mysqld shutdown

For killing process

# kill -TERM `ps axxwww | grep mysqld`

2) Run database with "skip grants" option

# /bin/sh /usr/bin/mysqld_safe --defaults-file=/etc/my.cnf \

--pid-file=/var/run/mysqld/mysqld.pid --skip-grant-tables

3) Log in into database and change password

# mysql 

mysql> use mysql;
mysql> update user set password=PASSWORD("newpassword") where user="root";
mysql> quit;

4) Restart database and log in with new password

To recover Postgresql password

1) Edit postgresql config file pg_hba.conf  and change line from :

 local   all postgres  peer

to 

local all postgres trust

2) Restart postgresql server :

# service postgresql restart 

3) Log in into database and change password

# psql -U postgres

postgres=# use template1
postgres-# alter user postgres with password 'secret';

postgres-# \q

4) Restart postgresql server