情况1：存在socket lock file

root用户执行 # systemctl restart kymysql 时不报错，但服务也没启动，查看错误日志

cat /opt/KY/Softs/log/mysql/mysql-error.log 
...
2021-06-18T01:28:47.783821Z 0 [Note] Server hostname (bind-address): '0.0.0.0'; port: 20001
2021-06-18T01:28:47.783838Z 0 [Note]   - '0.0.0.0' resolves to '0.0.0.0';
2021-06-18T01:28:47.783867Z 0 [Note] Server socket created on IP: '0.0.0.0'.
2021-06-18T01:28:47.783925Z 0 [ERROR] Another process with pid 2663 is using unix socket file.
2021-06-18T01:28:47.783932Z 0 [ERROR] Unable to setup unix socket lock file.
2021-06-18T01:28:47.783937Z 0 [ERROR] Aborting

解决办法：

# 删除sock锁文件
rm -rf /opt/KY/Softs/mysql/var/mysql.sock.lock
# 重启服务
systemctl restart kymysql

情况2：缺少lib包

root用户执行 # systemctl restart kymysql 时不报错，但服务也没启动，查看服务状态systemctl status kymysql :

● kymysql.service - MySql 5.7.26 database server
   Loaded: loaded (/usr/lib/systemd/system/kymysql.service; disabled; vendor preset: disabled)
   Active: inactive (dead)

6月 24 17:44:09 localhost.localdomain systemd[1]: Started MySql 5.7.26 database server.
6月 24 17:44:09 localhost.localdomain mysqld_safe[6507]: /opt/KY/Softs/mysql/bin/my_print_defaults: error while loading shared librar>
6月 24 17:44:09 localhost.localdomain mysqld_safe[6507]: /opt/KY/Softs/mysql/bin/my_print_defaults: error while loading shared librar>
6月 24 17:44:09 localhost.localdomain mysqld_safe[6507]: Logging to '/opt/KY/Database/localhost.localdomain.err'.
6月 24 17:44:09 localhost.localdomain mysqld_safe[6507]: 2021-06-24T09:44:09.430120Z mysqld_safe Starting mysqld daemon with database>
6月 24 17:44:09 localhost.localdomain mysqld_safe[6507]: 2021-06-24T09:44:09.448142Z mysqld_safe mysqld from pid file /opt/KY/Databas>
6月 24 17:44:09 localhost.localdomain systemd[1]: kymysql.service: Succeeded.

发现缺少lib包，直接运行mysqld： /opt/KY/Softs/mysql/bin/mysqld 发现缺少lib包：libatomic.so.1

/opt/KY/Softs/mysql/bin/mysqld: error while loading shared libraries: libatomic.so.1: cannot open shared object file: No such file or directory

解决办法：

# 安装缺少的包对应软件包
# 银河麒麟 libatomic.so.1 对应包名 libatomic
yum instll -y libatomic
# 重启服务
systemctl restart kymysql

附 mysql配置：

[client]
port        = 20001
socket      = /opt/KY/Softs/mysql/var/mysql.sock

[mysqld]
bind-address  = 0.0.0.0
port = 20001
socket      = /opt/KY/Softs/mysql/var/mysql.sock
user = root


basedir = /opt/KY/Softs/mysql
datadir = /opt/KY/Database
pid-file = /opt/KY/Database/mysql.pid

log_error = /opt/KY/Softs/log/mysql/mysql-error.log
slow_query_log = 1
long_query_time = 1
slow_query_log_file = /opt/KY/Softs/log/mysql/mysql-slow.log
back_log = 500

skip-external-locking
key_buffer_size = 256M
max_allowed_packet = 1024M
table_open_cache = 128
sort_buffer_size = 4M
net_buffer_length = 8K
read_buffer_size = 768K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 64M
thread_cache_size = 64
query_cache_size = 64M
tmp_table_size = 32M
performance_schema_max_table_instances = 1000
wait_timeout = 50

#explicit_defaults_for_timestamp = true
#skip-networking
max_connections = 1000
max_connect_errors = 10000000
open_files_limit = 65535

default_storage_engine = InnoDB
innodb_file_per_table = 1
innodb_buffer_pool_size = 128M
innodb_log_file_size = 32M
innodb_log_buffer_size = 8M
innodb_flush_log_at_trx_commit = 1
innodb_lock_wait_timeout = 50
innodb_file_format = Barracuda
innodb_strict_mode = 0

sql-mode 		= "NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"
lower_case_table_names 	= 1

由于时间仓促，错误与疏忽之处在所难免，希望各位朋友们以邮件的形式反馈问题给我，再次表示感谢！