Mac terminal ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

Looks like Mysql server has not started.

mysqld stop
mysql.server start

Had exactly the same issue, used the above command to fix it.

OSX 10.13.2 High Sierra
mariadb 10.2.12

I got the exact same error when I tried to use mariadb, which I installed with homebrew. The first thing I did after installing was:

$ mysql -u root
ERROR 2002 (HY000): Can't connect to local MySQL server through 
socket '/tmp/mysql.sock' (2)

To troubleshoot, I did:

~$ which mysql
/usr/local/mysql/bin/mysql

and then I tried:

~$ mysql -u 7stud -p test
 Enter password:
 ERROR 2002 (HY000): Can't connect to local MySQL server 
 through socket '/tmp/mysql.sock' (2)

and:

~$ mysql -u -p
ERROR 2002 (HY000): Can't connect to local MySQL server 
through socket '/tmp/mysql.sock' (2) 

The solution:

~$ mysql.server start
Starting MySQL
.180127 00:24:48 mysqld_safe Logging to '/usr/local/var/mysql/MyMBP.home.err'.
180127 00:24:48 mysqld_safe Starting mysqld daemon with databases from /usr/local/var/mysql
 SUCCESS! 

~$ mysql -u root
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 5.5.5-10.2.12-MariaDB Homebrew

Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

Okay, let's go:

mysql> show databases
    -> ;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| test               |
+--------------------+
4 rows in set (0.01 sec)

mysql> CREATE DATABASE my_db;
Query OK, 1 row affected (0.00 sec)

mysql> use my_db;
Database changed

mysql> show tables;
Empty set (0.01 sec)

mysql> CREATE TABLE people (
    -> id INT(12) not null auto_increment primary key, 
    -> name VARCHAR(40), 
    -> info VARCHAR(100)
    -> );
Query OK, 0 rows affected (0.03 sec)

mysql> describe people;
+-------+--------------+------+-----+---------+----------------+
| Field | Type         | Null | Key | Default | Extra          |
+-------+--------------+------+-----+---------+----------------+
| id    | int(12)      | NO   | PRI | NULL    | auto_increment |
| name  | varchar(40)  | YES  |     | NULL    |                |
| info  | varchar(100) | YES  |     | NULL    |                |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)

mysql> INSERT INTO people(name, info) VALUES("Joe", "a b c") ;
Query OK, 1 row affected (0.01 sec)

mysql> select * from people;
+----+------+-------+
| id | name | info  |
+----+------+-------+
|  1 | Joe  | a b c |
+----+------+-------+
1 row in set (0.00 sec)

mysql> INSERT INTO people(name, info) VALUES("Beth", "1 2 3") ;
Query OK, 1 row affected (0.00 sec)

mysql> select * from people;
+----+-------+-------+
| id | name  | info  |
+----+-------+-------+
|  1 | Joe   | a b c |
|  2 | Beth  | 1 2 3 |
+----+-------+-------+
2 rows in set (0.00 sec)

mysql> quit
Bye

~$ mysql.server stop
Shutting down MySQL
. SUCCESS! 
~$ 

The best instructions I found for manually starting and stopping mariadb are paradoxically at Starting and Stopping MariaDB Automatically:

You have the option of starting the mysqld server several different ways:

1. Run or invoke mysqld itself. An example of doing this is described more in Running MariaDB from the Source Directory.

2. Use the mysqld_safe startup script

3. Use the mysql.server startup script

The mysql.server script starts mysqld by first changing to the MariaDB install directory and then calling mysqld_safe. Adding an appropriate user line to the [mysqld] group in your my.cnf file will cause the server to be run as that user.

If you have installed MariaDB to a non-standard location, you may need to edit the mysql.server script to get it to work right.

mysql.server works as a standard SysV-style init script. As such you use the script with start and stop arguments like so:

mysql.server start
mysql.server stop

The error: Mac terminal ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

How I solved this on my MAC + MAMP (pro) setup:

sudo ln -s /Applications/MAMP/tmp/mysql/mysql.sock /tmp/mysql.sock

Which creates a symlink from /tmp/mysql.sock to the MAMP mysql.sock

Now restart MAMP and then the error should not occur again.