You need to specify the socket for the mysql client using the --socket=path option. You changed it in my.cnf (so either move it back - it probably belongs in /var/lib/mysql - or specify it every time). 

On 28 Jan 2012, at 1458, Philipp Schiffer wrote:

> Hi everybody,
> 
> thanks to fast help from several people mysql starts up:
> Starting mysqld:                                           [  OK  ]
> I had to "chcon -t var_t /data" to allow mysql to get through to /data, so special thanks to Chris and Stephan for that one.
> Anyway, now trying to get into mysql (as root) I do get
> ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
> and don't understand why that should be. Any suggestions?
> 
> Best
> 
> Phil
> 
> Am 28.01.12 21:31, schrieb Philipp Schiffer:
>> Hi!
>> 
>> Populating my mysql on SL6.1 with biological data I ran into my primary
>> SSDs limit and thus tried to move the location to another disk (HD). So
>> I sudo cp -R'ed everything from /var/lib/mysql to /data/mysqldata and
>> changed the permissions accordingly
>> drwxr-xr-x. 10 mysql mysql 4096 Jan 28 12:20 mysqldata
>> and inside mysqldata
>> drwx------. 2 mysql mysql 4096 Jan 28 12:20 b2g
>> -rw-r-----. 1 mysql mysql 178257920 Jan 28 20:50 ibdata1
>> -rw-r-----. 1 mysql mysql 5242880 Jan 28 20:50 ib_logfile0
>> -rw-r-----. 1 mysql mysql 5242880 Jan 28 20:50 ib_logfile1
>> drwx------. 2 mysql mysql 4096 Jan 28 12:20 mysql
>> drwx------. 2 mysql mysql 4096 Jan 28 12:20 orthotest
>> Then went on to modify /etc/my.cnf to
>> [mysqld]
>> #datadir=/var/lib/mysql
>> datadir=/data/mysqldata
>> #socket=/var/lib/mysql/mysql.sock
>> socket=/data/mysqldata/mysql.sock
>> user=mysql
>> # Disabling symbolic-links is recommended to prevent assorted security
>> risks
>> symbolic-links=0
>> #basedir=/data
>> 
>> [mysqld_safe]
>> log-error=/var/log/mysqld.log
>> pid-file=/var/run/mysqld/mysqld.pid.
>> 
>> Having stopped the server before doing all this I now started again, but
>> it failed to work. less /var/log/mysqld.log says:
>> 120128 21:03:08 mysqld_safe mysqld from pid file
>> /var/run/mysqld/mysqld.pid ended
>> 120128 21:09:06 mysqld_safe Starting mysqld daemon with databases from
>> /data/mysqldata
>> 120128 21:09:06 [Warning] Can't create test file
>> /data/mysqldata/superrechenknecht.lower-test
>> 120128 21:09:06 [Warning] Can't create test file
>> /data/mysqldata/superrechenknecht.lower-test
>> ^G/usr/libexec/mysqld: Can't change dir to '/data/mysqldata/' (Errcode: 13)
>> 120128 21:09:06 [ERROR] Aborting
>> 
>> 120128 21:09:06 [Note] /usr/libexec/mysqld: Shutdown complete
>> 
>> 120128 21:09:06 mysqld_safe mysqld from pid file
>> /var/run/mysqld/mysqld.pid ended
>> 
>> Tried to set a symbolic link from /var/lib/mysql -> /data/mysqldata but
>> that failed to work as well (actually why can't I change the ownership
>> of the link from root:root to mysql:mysql?). Finally reading up on
>> SElinux I edited my new mysql directory /data/mysqldata to look the same
>> as the original mysql folder:
>> drwxr-xr-x. mysql mysql system_u:object_r:mysqld_db_t:s0 mysqldata
>> drwxr-xr-x. mysql mysql system_u:object_r:mysqld_db_t:s0 mysql_old
>> 
>> and within mysqldata:
>> drwx------. mysql mysql system_u:object_r:mysqld_db_t:s0 b2g
>> -rw-r-----. mysql mysql unconfined_u:object_r:mysqld_db_t:s0 ibdata1
>> -rw-r-----. mysql mysql unconfined_u:object_r:mysqld_db_t:s0 ib_logfile0
>> -rw-r-----. mysql mysql unconfined_u:object_r:mysqld_db_t:s0 ib_logfile1
>> drwx------. mysql mysql unconfined_u:object_r:mysqld_db_t:s0 mysql
>> drwx------. mysql mysql unconfined_u:object_r:mysqld_db_t:s0 orthotest
>> drwx------. mysql mysql system_u:object_r:mysqld_db_t:s0 sknstuff_insp
>> 
>> However, even that does leads to the same error messages in the log file
>> and I am really at a loss. Any help with this would be highly
>> appreciated (especially as I need a working db quite urgently).
>> 
>> Tschöö
>> 
>> Philipp