(I seem to have a lot of trouble with Homebrew MySQL, huh?)

$ mysql -se "SHOW VARIABLES"

e.g.:

$ mysql -se "SHOW VARIABLES" | grep -e log_error -e general_log -e slow_query_log

Output (with the grep):

binlog_error_action    ABORT_SERVER  
general_log    OFF  
general_log_file    /usr/local/var/mysql/burritobear.log  
log_error    stderr  
log_error_verbosity    3  
slow_query_log    OFF  
slow_query_log_file    /usr/local/var/mysql/burritobear-slow.log