简述：此次主要是因为搬迁机房，原来一台09年的ubuntu安装的9.x的系统，后来升级过内核为10.x，上面服务配置混乱需要整理，领导想要升级系统，重装跟以前服务器上一样的软件。由于年代久远，现在系统升级为16.x比较难找到老版本source.list源，试过离线自己做本地源，依赖解决不了，最后再国外找到一个比较全的源。安装完成后，mysql没有配置文件，自己手动自定义有问题，最后经过查找帮助配置文件，解决，具体如下

[client]
port            = 3306
socket          = /var/run/mysqld/mysqld.sock
default-character-set=utf8
[mysqld]
port            = 3306
socket          = /var/run/mysqld/mysqld.sock

#一、不能创建mysqld.pid

#与my-innodb-heavy-4G.cnf比较,一定要修改成上面不然老是报错

#[ERROR] /usr/sbin/mysqld: Can't create/write to file '/var/run/mysqld/mysqld.pid' (Errcode: 13)

#[ERROR] Can't start server: can't create PID file: Permission denied

skip-external-locking
default-character-set=utf8
init_connect='SET NAMES utf8'
key_buffer              = 16M
max_allowed_packet      = 4M
thread_stack            = 256K
thread_cache_size       = 128
table_cache            = 1024
thread_concurrency     = 10
sort_buffer_size = 6M
read_buffer_size = 4M
join_buffer_size = 8M
myisam_sort_buffer_size = 16M
tmp_table_size = 128M
query_cache_limit       = 4M
query_cache_size        =32M
set-variable = innodb_buffer_pool_size= 4G
set-variable = innodb_additional_mem_pool_size=64M
myisam-recover          = BACKUP
max_connections        = 1000
expire_logs_days        = 10
max_binlog_size         = 100M
skip-federated

#二、链接文件修改配置文件错误

#另外注意这几个文件的连接情况

root@ubuntu16-slyey:/etc/mysql# ls -al /etc/mysql/my.cnf.fallback
-rwxr-xr-x 1 root root 833 Jan 11 15:17 /etc/mysql/my.cnf.fallback
root@ubuntu16-slyey:/etc/mysql# ls -al /etc/alternatives/my.cnf.fallback
lrwxrwxrwx 1 root root 26 Jan 11 14:56 /etc/alternatives/my.cnf.fallback -> /etc/mysql/my.cnf.fallback
root@ubuntu16-slyey:/etc/mysql# ls -al /etc/mysql/my.cnf
lrwxrwxrwx 1 root root 33 Jan 11 13:43 /etc/mysql/my.cnf -> /etc/alternatives/my.cnf.fallback

#三、排错方法

#重要的排错方法

#systemctl status mysql.service #查看状态信息

#journalctl -xe #查看具体错误信息

#四、mysql帮助文档查看，最后找到解决方法

#dpkg -L softname
#dpkg -s softname
#dpkg -S softname
#aptitude
#apt-file list softname
#/usr/share/doc/mysql-server-5.0/examples/my-large.cnf.gz
#/usr/share/doc/mysql-server-5.0/examples/my-small.cnf
#/usr/share/doc/mysql-server-5.0/examples/ndb_mgmd.cnf
#/usr/share/doc/mysql-server-5.0/examples/my-huge.cnf.gz
#/usr/share/doc/mysql-server-5.0/examples/my-innodb-heavy-4G.cnf.gz

#我是通过my-innodb-heavy-4G.cnf.gz这个文件来修改的