Mysql – debian thesql error running shared postrotate script for /var/log/thesql.log

It sounds like the mysql process (mysqld_safe, I believe) is unable to create the log file after you use logrotate to move it out of the way and send a HUP? If I'm way off here, let me know.

Assuming I'm not way off, there are a few options here:

• Move the log to a directory owned by the same user as the mysqld_safe process. For example, create a /var/log/mysqld/ directory and save the logfiles there. If the directory is mysql:mysql 700 then new files can be created without an issue.
• Use the copy/truncate logrotate method instead of the move/SIGHUP method. The copy/truncate method will copy the current log files (mysqld.slow.log) to a new file (mysqld.slow.log.1) then truncate the original file to zero bytes. This is useful if you don't want to interrupt the process that is writing to the log for some reason. The downside, of course, is that there is additional disk overhead with copying the original file to a new file before wiping the original file back to zero bytes. This is done by adding the copytruncate option to the logrotate stanza for that file and removing the no-longer-required postrotate section.

Make sure your start.sh is using the correct my.cnf with --defaults-file=/path/to/my.cnf

You may also have another my.cnf automatically being included (usually /etc/mysql/my.cnf) that could be adding/overriding options in your base config file.