mysqld --help --verbose creates a log-bin-index file

root@9ebc054fcde1:/# cat > /etc/mysql/conf.d/test.cnf

[mysqld]

bind-address=0.0.0.0

log-bin=foo-bin

console=1

general_log=1

general_log_file=/var/lib/mysql/mysql-general.log

slow_query_log=1

slow_query_log_file=/var/lib/mysql/mysql-slow.log

log_error=/var/lib/mysql/mysql-error.log

collation-server=utf8_unicode_ci

character-set-server=utf8

binlog_format=ROW

server_id=999

transaction-isolation=READ-COMMITTED

sync_binlog=1

sync_frm=1

log_output=TABLE,FILE

root@9ebc054fcde1:/# mysqld --help --verbose | grep general

2021-05-19  3:50:27 0 [Note] Plugin 'FEEDBACK' is disabled.

2021-05-19  3:50:27 0 [Warning] Could not open mysql.plugin table. Some options may be missing from the help text

  --general-log       Log connections and queries to a table or log file.

                      mysql.general_logif --log-output=TABLE is used.

  --general-log-file=name 

                      --relay-log-index, --general-log-file,

                      Don't log certain types of statements to general log. Any

                      Log some not critical warnings to the general log

general-log                                                TRUE

general-log-file                                           /var/lib/mysql/mysql-general.log

root@9ebc054fcde1:/# mysqld --help --verbose | grep log-bin

2021-05-19  3:50:37 0 [Note] Plugin 'FEEDBACK' is disabled.

2021-05-19  3:50:37 0 [Warning] Could not open mysql.plugin table. Some options may be missing from the help text

                      names for --log-bin, --log-bin-index, --relay-log,

  --log-bin[=name]    Log update queries in binary format. Optional argument

  --log-bin-compress  Whether the binary log can be compressed

  --log-bin-compress-min-len[=#] 

  --log-bin-index=name 

  --log-bin-trust-function-creators 

                      If set to FALSE (the default), then when --log-bin is

log-bin                                                    foo-bin

log-bin-compress                                           FALSE

log-bin-compress-min-len                                   256

log-bin-index                                              (No default value)

log-bin-trust-function-creators                            FALSE

root@9ebc054fcde1:/# ls -la /var/lib/mysql

total 8

drwxr-xr-x. 2 root root 4096 May 19 03:50 .

drwxr-xr-x. 8 root root 4096 May 13 17:21 ..

-rw-rw----. 1 root root    0 May 19 03:50 foo-bin.index