I was looking for where mysql.sock was since running rake db:bootstrap was complaining with “No such file or directory – /tmp/mysql.sock”. Rails looks for the mysql.sock file under /tmp/mysql.sock by default. Ubuntu using an apt-get install of mysql puts the mysql.sock file at /var/run/mysqld/mysqld.sock.

I always forget where it is. So, I’m writing it down.

/var/run/mysqld/mysqld.sock

You can also grep for it from mysql like so

>>  mysql -? | grep mysqld.sock
socket                            /var/run/mysqld/mysqld.sock