How does afl-cov collect program of C/S architecture(such as mysql) code coverage?

[likaiam]

I have using fuzzed mysql and generated some seed file.Now I want to use afl-cov to collect mysql code coverage.I use the following command:
/home/mysql/afl-cov/afl-cov -d /home/mysql/fuzzing/fuzz_output --enable-branch-coverage -c . -e "cat AFL_FILE |./bld_aflcov/bin/mysqld" or /home/mysql/afl-cov/afl-cov -d /home/mysql/fuzzing/fuzz_output --enable-branch-coverage -c . -e "cat AFL_FILE |./bld_aflcov/bin/mysql"
But it doesn't work