How To Properly Turn On MySQL Error Logging?

Question

I currently have "err-log=/var/log/mysqld.log" under the "[safe_mysqld]" section. I was under the impression that it should be under the "[mysqld]". Am I right about that? Should I move it there to turn it on? Why is it under the [safe_mysqld] section?

Also, I noticed that the log file didn't exist at all for me, so I created it with mysql as its owner. Still, the file isn't being written to.

Thanks a lot.

EDIT: A side question, if you don't mind: I have the line "user=mysqlbasedir=/var/lib" under "[mysql.server]". I've seen in other sample files that those are two separate lines, user and basedir. Why are they together as one line? I tried separating them, and mysql failed to start as a result. Thanks.