How to Set character sets based on mysql 5.5

I installed a mysql on the virtual machine, modified its my. cof file, and found that this configuration file is powerful, but encountered a problem:

When setting character sets, set default-character-set = utf8 under [client], [mysql], and [mysqld], but the following problems occur:

One by one troubleshooting, it is found that it is caused by setting default-character-set = utf8 under [mysqld. View the/var/lib/mysql/$ {hostname}. err file:

The problem is that mysqld does not recognize default-character-set. I checked some information online and found that setting character_set_server = utf8 under mysqld is good.

View character set:Show variables like 'character % ';