Ubuntu 11.04 - Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (13)

Question

I have googled for 2 days now and was initially get a

'/var/run/mysqld/mysqld.sock' (2)

I fixed this by using:

sudo touch /var/run/mysqld/mysqld.sock
sudo chown -R mysql /var/run/mysqld/

now i get the error:

 '/var/run/mysqld/mysqld.sock' (13)

So everything has the correct permissions and the file exists. Any thoughts?

[Edit]

Got it working, although i am unsure how. I did aa-logprof as root, nothing changed, got angry and then re-set it started working.

Answer 1

In my case, running mysqld_safe created a new mysqld.sock file.

$ cd /etc/init.d/
$ mysqld_safe

You'll probably won't get the prompt back, but if you restart your session, a mysqld.sock file will be somewhere. Find it with

$ sudo find / -type s | grep mysqld.sock

Answer 2

You cannot (absolutely cannot) replace the filesystem pipe /var/run/mysqld/mysql.sock with a regular file. You need to use mkfifo(1) to create the pipe(7) that clients use to communicate with the mysql server.

The (13) probably also means that you have a permission denied error return, EACCES (which usually has the decimal value 13 -- yes, I've seen it a lot).

If the file system permissions are configured correctly, you might be having accesses rejected by a mandatory access control tool such as AppArmor, SELinux, TOMOYO, or SMACK.

AppArmor comes pre-installed on Ubuntu systems by default, and might be rejecting access to the pipe. Check /var/log/syslog, /var/log/audit/audit.log or dmesg(1) output for messages that look something like this:

type=AVC msg=audit(1320723925.179:45115): apparmor="DENIED"
operation="open" parent=1 profile="/usr/sbin/ntop"
name="/usr/share/ntop/html/PlotKit/excanvas.js" pid=1835 comm="ntop"
requested_mask="r" denied_mask="r" fsuid=122 ouid=0

(But with name=/var/run/mysqld/mysql.sock instead.)

If you have error messages like this, run aa-logprof as root and answer the questions. More information on configuration AppArmor can be found in the apparmor.d(5) manpage, or some various wiki pages.