For homebrew mysql installs, where's my.cnf?

There is no my.cnf by default. As such, MySQL starts with all of the default settings. If you want to create your own my.cnf to override any defaults, place it at /etc/my.cnf.

Also, you can run mysql --help and look through it for the conf locations listed.

Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf /usr/etc/my.cnf ~/.my.cnf 
The following groups are read: mysql client
The following options may be given as the first argument:
--print-defaults        Print the program argument list and exit.
--no-defaults           Don't read default options from any option file.
--defaults-file=#       Only read default options from the given file #.
--defaults-extra-file=# Read this file after the global files are read.

As you can see, there are also some options for bypassing the conf files, or specifying other files to read when you invoke mysql on the command line.

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The homebrew mysql contains sample configuration files in the installation's support-files folder.

ls $(brew --prefix mysql)/support-files/my-*

If you need to change the default settings you can use one of these as a starting point.

cp $(brew --prefix mysql)/support-files/my-default.cnf /usr/local/etc/my.cnf

As @rednaw points out, a homebrew install of MySQL will most likely be in /usr/local so the my.cnf file should not be added to the system /etc folder, so I’ve changed the command to copy the file into /usr/local/etc.

If you are using MariaDB rather than MySQL use the following:

cp $(brew --prefix mariadb)/support-files/my-small.cnf /usr/local/etc/my.cnf

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One way to find out:

sudo /usr/libexec/locate.updatedb
# wait a few minutes for it to finish
locate my.cnf

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in my system it was

nano /usr/local/etc/my.cnf.default 

as template and

nano /usr/local/etc/my.cnf

as working.

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Since mysql --help shows a list of files, I find it useful to pipe the result to ls to see which of them exist:

$ mysql --help | grep /my.cnf | xargs ls
ls: /etc/my.cnf: No such file or directory
ls: /etc/mysql/my.cnf: No such file or directory
ls: ~/.my.cnf: No such file or directory
/usr/local/etc/my.cnf

For my (Homebrew installed) MySQL 5.7, it seems the files is on /usr/local/etc/my.cnf.

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Nothing really helped me - I could not overwrite settings in a /etc/my.cnf file. So I searched like John suggested https://stackoverflow.com/a/7974114/717251

sudo /usr/libexec/locate.updatedb
# wait a few minutes for it to finish
locate my.cnf

It found another my.cnf in

/usr/local/Cellar/mysql/5.6.21/my.cnf

changing this file worked for me! Don't forget to restart the launch Agent:

launchctl unload ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist
launchctl load ~/Library/LaunchAgents/homebrew.mxcl.mysql.plist

Update:

If you have a fairly recent installation of homebrew you should use the brew services commands to restart mysql (use your installed homebrew mysql version, i.e. mysql or mysql@5.7):

brew services stop mysql
brew services start mysql

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On your shell type my_print_defaults --help

At the bottom of the result, you should be able to see the file from which the server reads the configurations. It prints something like this:

Default options are read from the following files in the given order:
/etc/my.cnf /etc/mysql/my.cnf /usr/local/etc/my.cnf ~/.my.cnf

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Add another answer cause

The accepted is wrong. We're talking about Homebrew installed mysql, not MySQL installed manually.

The former answers may be a little outdated, Homebrew on M1 Mac is stored in a different location

Conf

The my.cnf is copied by Homebrew to following places during installation

/usr/local/etc/my.cnf for x86 Mac

/opt/homebrew/etc/my.cnf for M1 Mac

Homebrew chooses /usr/local, or /opt/homebrew to store packages, so the default conf files are not stored in /etc/ but /usr/local/etc or /opt/homebrew/etc.

In fact, homebrew changed the -DSYSCONFDIR= (default conf location) flag during compiling mysql from source.

Start the Service

A short answer: run brew info mysql and check the tips.

The recommended way is brew services start mysql, which uses the launchd to manage services. (launchd is deemed a systemd alternative on macOS)

For anyone wanna start it manually, mysql.start without any option is enough to start the service. (mysql.start is a script provided by mysql to help start the service)

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Server version: 8.0.19 Homebrew. macOS Catalina 10.15.5 and installed MySQL via Homebrew. Found this file here:

/usr/local/etc/my.cnf

This solution helped :)

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You can find where the my.cnf file has been provided by the specific package, e.g.

brew list mysql # or: mariadb

In addition to verify if that file is read, you can run:

sudo fs_usage | grep my.cnf

which will show you filesystem activity in real-time related to that file.

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I believe the answer is no. Installing one in ~/.my.cnf or /usr/local/etc seems to be the preferred solution.

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In case of Homebrew, mysql would also look for my.cnf in it's Cellar directory, for example:

/usr/local/Cellar/mysql/5.7.21/my.cnf

For the case one prefers to keep the config close to the binaries - create my.cnf here if it's missing.

Restart mysql after change:

brew services restart mysql

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run

sudo find / -name my.cnf

Usually the first result is the correct one. Should be in

/usr/local/etc/

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If you are using mac m1 (Apple silicon), the my.cnf is located at

/opt/homebrew/etc/my.cnf

and can also be found by mysql --help

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I have installed MySQL 5.7 using Homebrew

my.cnf file is located in "/opt/homebrew/etc/my.cnf"

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For MacOS (High Sierra), MySQL that has been installed with home brew.

Increasing the global variables from mysql environment was not successful. So in that case creating of ~/.my.cnf is the safest option. Adding variables with [mysqld] will include the changes (Note: if you change with [mysql] , the change might not work).

<~/.my.cnf> [mysqld] connect_timeout = 43200 max_allowed_packet = 2048M net_buffer_length = 512M

Restart the mysql server. and check the variables. y

sql> SELECT @@max_allowed_packet; +----------------------+ | @@max_allowed_packet | +----------------------+ | 1073741824 | +----------------------+

1 row in set (0.00 sec)

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$ps aux | grep mysqld /usr/local/opt/mysql/bin/mysqld --basedir=/usr/local/opt/mysql --datadir=/usr/local/var/mysql --plugin-dir=/usr/local/opt/mysql/lib/plugin Drop your my.cf file to /usr/local/opt/mysql brew services restart mysql

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