Where is my mysql log on OS X?

I checked /var/log and /usr/local/mysql and i can't seem to find the log. I am trying to troubleshoot an error establishing a database connection with a php function.

Solution 1:

As Chealion mentioned, there are several ways that your mysql could have been installed. Each of which will place your data dir and/or logs in different locations. The following command will give you (and us) a good indication of where to look.

ps auxww|grep [m]ysqld

# Putting brackets around the first char is a `grep`+`ps` trick
# to keep it from matching its own process.
# Note: For zsh compatibility put quotes around the grep regex

Can you post the result of that command here please? Mine looks like this:

_mysql     101   0.0  0.3   112104  13268   ??  S    12:30AM   0:13.20 /opt/local/libexec/mysqld --basedir=/opt/local --datadir=/opt/local/var/db/mysql --user=mysql --pid-file=/opt/local/var/db/mysql/rbronosky-mbp.pid
root        76   0.0  0.0   600172    688   ??  S    12:30AM   0:00.02 /bin/sh /opt/local/lib/mysql/bin/mysqld_safe --datadir=/opt/local/var/db/mysql --pid-file=/opt/local/var/db/mysql/rbronosky-mbp.pid

From that you can see that my datadir is /opt/local/var/db/mysql (because I installed via MacPorts). Let's take this lesson a bit further...

From the first line you can see the my daemon is /opt/local/libexec/mysqld. The mysqld can be called with --verbose --help to get a list of all command line options (and here is the important/valuable part!) followed by the values that would be used if you were launching mysqld instead of just checking the help output. The values are the result of your compile time configuration, my.cnf file, and any command line options. I can exploit this feature to find out EXACTLY where my log files are, like so:

/opt/local/libexec/mysqld --verbose --help|grep '^log'

Mine looks like this:

log                               /tmp/mysql.log
log-bin                           /tmp/mysql-bin
log-bin-index                     (No default value)
log-bin-trust-function-creators   FALSE
log-bin-trust-routine-creators    FALSE
log-error                         /tmp/mysql.error.log
log-isam                          myisam.log
log-queries-not-using-indexes     FALSE
log-short-format                  FALSE
log-slave-updates                 FALSE
log-slow-admin-statements         FALSE
log-slow-queries                  (No default value)
log-tc                            tc.log
log-tc-size                       24576
log-update                        (No default value)
log-warnings                      1

LO AND BEHOLD! all of the advice in the world was not going to help me because my log file is kept in a completely non-standard location! I keep mine in /tmp/ because on my laptop, I don't care (actually I prefer) to loose all of my logs on reboot.

Let's put it all together and make you a oneliner:

$(ps auxww|sed -n '/sed -n/d;/mysqld /{s/.* \([^ ]*mysqld\) .*/\1/;p;}') --verbose --help|grep '^log'

Execute that one command and you will get a list of all of the logs for your running instance of mysql.

Enjoy!

This Bash-Fu brought to you for free by my commitment to all things Open Source.

Solution 2:

There are 3 types of MySQL/MariaDB logs:

• log_error for the error message log;
• general_log_file for the general query log file (if enabled by general_log);
• slow_query_log_file for the slow query log file (if enabled by slow_query_log);

Check the settings and location of above logs by this shell command:

mysql -se "SHOW VARIABLES" | grep -e log_error -e general_log -e slow_query_log

By default the logs are stored in your data dir, so check location by this shell command:

mysql -se "SELECT @@datadir"

To view your error log, you can run:

sudo tail -f $(mysql -Nse "SELECT @@log_error")

If you've general log enabled, to view it, run:

sudo tail -f $(mysql -Nse "SELECT CONCAT(@@datadir, @@general_log_file)")

Solution 3:

Another way to find this information is to use lsof.

1. Use Activity Monitor to find the PID of mysql, or use ps -ef | grep mysqld to find it.

2. sudo lsof -p PID_OF_MYSQLD and see which files MySQL has open.