Can't connect to local MySQL server through so

Question

I am having a big problem trying to connect to mysql. When I run:

/usr/local/mysql/bin/mysql start

I have the following error :

Can't connect to local MySQL server through socket '/var/mysql/mysql.sock' (38)

I do have mysql.sock under the /var/mysql directory.

In /etc/my.cnf I have:

[client]
port=3306
socket=/var/mysql/mysql.sock

[mysqld]
port=3306
socket=/var/mysql/mysql.sock
key_buffer_size=16M
max_allowed_packet=8M

and in /etc/php.ini I have :

; Default socket name for local MySQL connects.  If empty, uses the built-in
; MySQL defaults.
mysql.default_socket = /var/mysql/mysql.sock

I have restarted apache using sudo /opt/local/apache2/bin/apachectl restart

But I still have the error.

Otherwise, I don't know if that's relevant but when I do mysql_config --sockets I get

--socket         [/tmp/mysql.sock]

Answer 1

For those whose any solution did not work, try:

cd /etc/mysql

check if my.cnf is present

nano my.cnf

and make sure you have only one bind-address as follows:

bind-address = 127.0.0.1

If not, that might be the problem, just exit nano and save the file.

and service mysql start

note that if you don't have nano (its a text editor) just install it with apt-get install nano and once in just press Ctrl+X to exit, dont forget to say Y to save and use the same file)

Answer 2

For me - this was simply a case of MySQL taking a long time to load. I have over 100,000 tables in one of my databases and it did eventually start but obviously has to take a long time in this instance.

Answer 3

As can be seen by the many answers here, there are lots of problems that can result in this error message when you start the MySQL service. The thing is, MySQL will generally tell you exactly what's wrong, if you just look in the appropriate log file.

For example, on Ubuntu, you should check /var/log/syslog. Since lots of other things might also be logging to this file, you probably want to use grep to look at mysql messages, and tail to look at only the most recent. All together, that might look like:

grep mysql /var/log/syslog | tail -50

Don't blindly make changes to your configuration because someone else said 'This worked for my system.' Figure out what is actually wrong with your system and you'll get a better result much faster.

Answer 4

I had this problem too when trying to start the server, so many of the answers here that just say to start the server didn't work. The first thing you can do is execute the following to see if there are any config errors:

/usr/sbin/mysqld --verbose --help 1>/dev/null

I did have one error that showed up:

160816 19:24:33 [Note] /usr/sbin/mysqld (mysqld 5.5.50-0ubuntu0.14.04.1-log) starting as process 9461 ...
160816 19:24:33 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
160816 19:24:33 [Note] Plugin 'FEDERATED' is disabled.
160816 19:24:33 [ERROR] /usr/sbin/mysqld: unknown variable 'innodb-online-alter-log-max-size=4294967296'
160816 19:24:33 [ERROR] Aborting

A simple grep -HR "innodb-online-alter-log-max-size" /etc/mysql/ showed me exactly what file contained the offending line, so I removed that line from the file.

Then, checking my /var/log/mysql/error.log file I had:

InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes
InnoDB: than specified in the .cnf file 0 671088640 bytes!
160816 22:46:46 [ERROR] Plugin 'InnoDB' init function returned error.
160816 22:46:46 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
160816 22:46:46 [ERROR] Unknown/unsupported storage engine: InnoDB
160816 22:46:46 [ERROR] Aborting

Based on this question the accepted solution wouldn't work because I couldn't even get the server started, so I followed what some of the comments said and deleted my /var/lib/mysql/ib_logfile0 and /var/lib/mysql/ib_logfile1 files.

This allowed the server to start and I was able to connect and execute queries, however checking my error log file it was quickly getting filled up with several tens of thousands of lines like this:

160816 22:52:15  InnoDB: Error: page 1415 log sequence number 82039318708
InnoDB: is in the future! Current system log sequence number 81640793100.
InnoDB: Your database may be corrupt or you may have copied the InnoDB
InnoDB: tablespace but not the InnoDB log files. See
InnoDB: http://dev.mysql.com/doc/refman/5.5/en/forcing-innodb-recovery.html
InnoDB: for more information.

Based on a suggestion from here, to fix this I did a mysqldump and restore of all databases (see the link for several other solutions).

$ mysqldump -u root -p --allow-keywords --add-drop-database --comments --hex-blob --opt --quote-names --databases db_1 db_2 db_3 db_etc > backup-all-databases.sql
$ mysql -u root -p < backup-all-databases.sql

Everything appears to be working as expected now.

Answer 5

I ran into this issue today. None of these answers provided the fix. I needed to do the following commands (found here https://stackoverflow.com/a/20141146/633107) for my mysql service to start:

sudo /etc/init.d/mysql stop
cd /var/lib/mysql/
ls ib_logfile*
mv ib_logfile0 ib_logfile0.bak
mv ib_logfile1 ib_logfile1.bak
... etc ...
/etc/init.d/mysql restart

This was partly indicated by the following errors in /var/log/mysql/error.log:

140319 11:58:21 InnoDB: Completed initialization of buffer pool
InnoDB: Error: log file ./ib_logfile0 is of different size 0 50331648 bytes
InnoDB: than specified in the .cnf file 0 5242880 bytes!
140319 11:58:21 [ERROR] Plugin 'InnoDB' init function returned error.
140319 11:58:21 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
140319 11:58:21 [ERROR] Unknown/unsupported storage engine: InnoDB
140319 11:58:21 [ERROR] Aborting

I also saw the disk full error, but only when running commands without sudo. If the permissions check fails, it reports disk full (even when your partition is not even close to full).

Answer 6

I used 127.0.0.1 for -h instead localhost and everything was OK. In other case had what had - error that above.