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this is somewhat of a mystery to me. The only way I can connect to MySQL is if I call it via "127.0.0.1" ... for example, my PHP connect script will NOT work with localhost

I'm running Mac OS X Lion, built-in apache2, MySQL, PHP, phpMyAdmin

mysqladmin:

count 0 debug-check FALSE debug-info TRUE force FALSE compress FALSE character-sets-dir (No default value) default-character-set auto host (No default value) no-beep FALSE port 0 relative FALSE socket (No default value) sleep 0 ssl FALSE ssl-ca (No default value) ssl-capath (No default value) ssl-cert (No default value) ssl-cipher (No default value) ssl-key (No default value) ssl-verify-server-cert FALSE user (No default value) verbose FALSE vertical FALSE connect-timeout 43200 shutdown-timeout 3600 plugin-dir (No default value) default-auth (No default value)
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    This is probably more for Server fault, but make sure your hosts file has the localhost alias. Commented Jul 28, 2011 at 22:13
  • 127.0.0.1 localhost is in my hosts file. Commented Jul 28, 2011 at 22:16
  • Open command prompt and type ping localhost and see what it says. Commented Jul 28, 2011 at 22:20
  • 64 bytes from 127.0.0.1: icmp_seq=0 ttl=64 time=0.100 ms 64 bytes from 127.0.0.1: icmp_seq=1 ttl=64 time=0.102 ms 64 bytes from 127.0.0.1: icmp_seq=2 ttl=64 time=0.096 ms Commented Jul 28, 2011 at 22:35

11 Answers 11

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MySQL will try to connect to the unix socket if you tell it to connect to "localhost". If you tell it to connect to 127.0.0.1 you are forcing it to connect to the network socket. So probably you have MySQL configured to only listen to the network socket and not to the file system socket.

What exactly is wrong with your unix socket is hard to tell. But I recommend you to read this page on the MySQL reference guide. This should help you.

UPDATE: Based on the updated question: The parameter "socket" should be something like this: "/var/lib/mysql/mysql.sock". This page in the Reference Manual has some more information.

Here you have the beginning of my /etc/my.cnf file:

[mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock

Your file should be similar. Then your problem should be solved. Don't forget to restart the MySQL server before you test it.

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    Wow: "A Unix socket file is used if you don't specify a host name or if you specify the special host name localhost." That seems...unintuitive. Hence all the other answers. Commented Jul 28, 2011 at 23:41
  • Thats good to know +1 Commented Jul 29, 2011 at 1:03
  • I appreciate the theory... just don't know what the answer is. Commented Jul 30, 2011 at 4:49
  • @dcolumbus: As I already wrote it is hard to tell. What I can recommend you is to open a console and just write the command "mysql". Maybe you get more information then. Another thing is to look into the log file. Mine is located in the directory /var/log/ and is called mysql.log. Yours could have another name or another location. If you can provide us with more information then we can probably help you better. Commented Jul 30, 2011 at 10:59
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    php.ini has references to "/var/mysql/mysql.sock" (3 places to be exact) which need to be changed to "/tmp/mysql.sock" ... Thank you for your help! Commented Aug 3, 2011 at 22:00
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You may have IPv6 enabled, its very possible localhost resolves to the ipv6 localhost, that is not defined in your msql config.

ive also had a problem where i had to add 'localhost' in place of '127.0.0.1' to the allowed subnets for that user, dont understand why (i was using ipv4 and it was a while ago) but its worth a try.

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  • You can check this by seeing if 'host localhost' at the command line returns ::1 as well as 127.0.0.1. If so, you can either remove the ::1 mapping from /private/etc/hosts or reconfigure MySQL to listen on the IPv6 ::1 address as well as 127.0.0.1 Commented Jul 28, 2011 at 22:42
  • I think I remember reading somewhere that IPv6 is enabled by default on Mac OS X ... is that the case? Commented Jul 28, 2011 at 23:07
  • ipv6 is enabled for pretty much all modern OS's these days, im on osx10.6 and its enabled by default. Commented Jul 29, 2011 at 2:13
  • wrong. Localhost has special meaning for mysql clients — check out serverfault.com/a/295300/67675 Commented Jan 29, 2019 at 3:39
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For me, OSX's builtin php is configured to use a different unix-socket than homebrew's mysql. Thus it can't connect via localhost which utilizes that socket.

I fixed it with a quick hack by symlinking php's configured socket-path to point to the one mysql actually uses.

sudo ln -s /tmp/mysql.sock /var/mysql/mysql.sock

The following diagnostic commands were very helpful.

Check the default socket-paths used by php and mysql:

php -i | fgrep 'mysql.default_socket' mysql -e 'show variables where variable_name = "socket"'

Connect using a specified socket:

php -r 'var_dump(mysql_connect("localhost:/tmp/mysql.sock", "user", "pass"));' mysql --socket=/tmp/mysql.sock

Determine what kind of socket mysql client is using to connect:

lsof | egrep '^mysql .*(IPv|unix)'
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Could you check mysql/conf/my.conf (the directory structure should pretty much be the same on OSx) to see if skip-networking is uncommented? If so, add a # in-front of the line and restart the mysql-server.

I actually had a similar issue a while back (although that wasn't in OSx), so I thought it might be worth a shot.

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    Why did this get downvoted? An explanation would be helpful. Commented Jul 31, 2011 at 18:44
  • I didn't down-vote you, but your answer is actually the opposite of what the OP is asking. But I upvoted you because I struggled with the opposite condition — would connect via a socket, but NOT via network. By the way, I COULD NOT fix this via my.conf; I had to put it on the command line: "mysqlf --skip_networking=0 ..." Commented Feb 14, 2015 at 13:00
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I was able to recreate your same symptoms on my test box, hopefully this will help.

In MySQL, users are defined by two parts (name and host). By default, MySQL will have 3 root users:

mysql> SELECT host,user,password FROM mysql.user WHERE user='root'; +-----------------------+------+-------------------------------------------+ | host | user | password | +-----------------------+------+-------------------------------------------+ | localhost | root | | | localhost.localdomain | root | | | 127.0.0.1 | root | *PASSWORD_HASH_GOES_HERE | +-----------------------+------+-------------------------------------------+

The password field will either be blank (no password) or have a hash stored. If you set the password for one specific user, it doesn't automatically update all, since MySQL sees them as different users.

For example:

mysql> set password for 'root'@'127.0.0.1' = password('Password');

will update the password for 'root'@'127.0.0.1', but not 'root'@'localhost' or 'root'@'localhost.localdomain'

Take a look at the skip_name_resolve variable:

mysql> show variables like 'skip_name_resolve'; +-------------------+-------+ | Variable_name | Value | +-------------------+-------+ | skip_name_resolve | ON | +-------------------+-------+ 1 row in set (0.00 sec)

By Default skip_name_resolve is OFF, and will attempt to resolve all IP Addresses to hostnames. For example, if you connect as 'root'@'127.0.0.1', MySQL will change connect you as 'root'@'localhost'.

If it is ON, MySQL will see and connect 'root'@'127.0.0.1' and 'root'@'localhost' as seperate users. And they may or may not have different passwords, depending on how they were set.

So first, I would check to see any password differences: mysql> SELECT host,user,password FROM mysql.user WHERE user='root';

If there are, you can fix them, or you can continue investigating.

Then I would check skip_name_resolve: mysql> show variables like 'skip_name_resolve';

If it is ON, I would find out where it's being set (for example /etc/my.cnf) and remove it, unless there is a need for it.

Hopefully this helps you out!

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PHP is still trying to use the default socket location. This problem can appear if you have moved the MariaDB/MySQL folder from /var/lib/mysql to another location. In order to solve the problem you have to define the new socket's location in the /etc/php.ini file.

mysqli.default_socket =/newDBLocation/mysql/mysql.sock

Watch out, depending on which driver you use, you may have to specify the pdo_mysql.default_socket=!

In order to check your current directory run the following command in mysql:

select @@datadir;
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For people who are using CageFS with CloudLinux:

I recreated /var/lib/mysql because I was rebuilding MySQL server from scratch...

which unmounted the path from cagefs. I know it's unrelated, but I was using cPanel and CloudLinux. I couldn't verify why socket connection won't work, and finally, I realized.

adding /var/lib/mysql to /etc/cagefs/cagefs.mp (if already there proceed to next step) and running 

cagefsctl --remount-all

fixed the problem

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    OMG! This is what fixed it for me! It was already in /etc/cagefs/cagefs.mp but running cagefsctl --remount-all fixed it. Thanks man! Commented Jul 8, 2019 at 14:14
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Is localhost defined in your /private/etc/hosts file?

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  • 127.0.0.1 localhost is in my hosts file. Commented Jul 28, 2011 at 22:16
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    /private? Never seen that before Commented Jul 29, 2011 at 11:04
  • @TheLQ: It's a Mac thing. While there is a symlink from /etc to /private/etc, for some reason Apple generally advises using the "true" path: support.apple.com/kb/TA27291 Commented Aug 4, 2011 at 21:42
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I was having this issue and I could not figure it out. I tried everything I could fine to no avail.

I found that I had a .netrc in /root/ that had info in it.

I deleted it and problem gone.

Able to log into mysql using mysql -uroot -p without issue now.

I know this is an old post but hope this helps someone.

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For me, changing the permissions to be publically readable on the parent directory of the mysql.sock fixed the issue: 

chmod 755 /var/lib/mysql
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you have to define it in private/etc/hosts I think... or just use 127.0.0.1 because it is the same thing anyhow, just an alias.

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  • 127.0.0.1 localhost is in my hosts file. Commented Jul 28, 2011 at 22:16

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