Fedora 16 strange /tmp permissions: thesqld will not start

You probably have bad file context on /tmp directory. Show us ls -ldZ /tmp.

How is it possible that temporary file inside /tmp has httpd_sys_content_t fcontext?

type=AVC msg=audit(1311581788.889:12363): avc:  denied  { write } for  pid=22102 comm="mysqld" path="/tmp/#sql_151e_0.MYI" dev=dm-0 ino=103481390 scontext=root:system_r:mysqld_t:s0 tcontext=root:object_r:httpd_sys_content_t:s0 tclass=file
        Was caused by:
                Missing or disabled TE allow rule.
                Allow rules may exist but be disabled by boolean settings; check boolean settings.
                You can see the necessary allow rules by running audit2allow with this audit message as input.

On RHEL it is:

ls -ldZ /tmp
drwxrwxrwt. root root system_u:object_r:tmp_t:s0       /tmp

For sure it has nothing to do with path for your backup file. If it would be permission problem, you would get something like this:

# su -s /bin/bash nobody -c 'mysqldump -uroot -p123456 --opt test > /root/test-`date +%d%m%Y`.sql'
bash: /root/test-13112013.sql: Permission denied

You can use strace -f -ff -o /tmp/strace mysqldump -uroot -ppassword --opt c2duo_db to see, which files it tries to open, use...

The package mysql is the client package. You need to install the server package:

$ sudo yum install mysql-server

Additionally, starting in Fedora 19, MariaDB is now the default implementation of MySQL. MariaDB is a fork of MySQL.

MariaDB, a community developed fork of MySQL, will be the default implementation of MySQL in Fedora 19.

source: https://fedoraproject.org/wiki/Features/ReplaceMySQLwithMariaDB