mysql：mysqld、mysqld_safe、mysql、

MYSQL 啓動：

mysqld — The MySQL Server

mysqld, also known as MySQL Server, is the main program that does most of the work in a MySQL installation. MySQL Server manages access to the MySQL data directory that contains databases and tables. The data directory is also the default location for other information such as log files and status files.

When MySQL server starts, it listens for network connections from client programs and manages access to databases on behalf of those clients.

The mysqld program has many options that can be specified at startup. For a complete list of options, run this command：

shell> mysqld --verbose --help

mysqld_safe — MySQL Server Startup Script

mysqld_safe  is the recommended way to start a  mysqld  server on Unix.  mysqld_safe  adds some safety features such as restarting the server when an error occurs and logging runtime information to an error log file. A description of error logging is given later in this section.

mysqld_safe Options

 

Format	Description	Introduced
--basedir	Path to MySQL installation directory
--core-file-size	Size of core file that mysqld should be able to create
--datadir	Path to data directory
--defaults-extra-file	Read named option file in addition to usual option files
--defaults-file	Read only named option file
--help	Display help message and exit
--ledir	Path to directory where server is located
--log-error	Write error log to named file
--malloc-lib	Alternative malloc library to use for mysqld
--mysqld	Name of server program to start (in ledir directory)
--mysqld-safe-log-timestamps	Timestamp format for logging	5.7.11
--mysqld-version	Suffix for server program name
--nice	Use nice program to set server scheduling priority
--no-defaults	Read no option files
--open-files-limit	Number of files that mysqld should be able to open
--pid-file	Path name of process ID file
--plugin-dir	Directory where plugins are installed
--port	Port number on which to listen for TCP/IP connections
--skip-kill-mysqld	Do not try to kill stray mysqld processes
--skip-syslog	Do not write error messages to syslog; use error log file
--socket	Socket file on which to listen for Unix socket connections
--syslog	Write error messages to syslog
--syslog-tag	Tag suffix for messages written to syslog
--timezone	Set TZ time zone environment variable to named value
--user	Run mysqld as user having name user_name or numeric user ID user_id

 

/home/mypath/mysql/bin/mysqld_safe --defaults-file=/home/mypath/mysql/etc/my.cnf

 /home/mypath/mysql/bin/mysqld --defaults-file=/home/mypath/mysql/etc/my.cnf --basedir=/home/my/mysql --datadir=/home/mypath/mysql/data --plugin-dir=/home/mypath /mysql/lib/plugin --log-error=/home/mypath/mysql/log/mysql.err --pid-file=/home/mypath/mysql/tmp/mysql.pid --socket=/home/mypath/mysql/tmp/mysql.sock --port=3377

Unix系統下本地鏈接MySQL能夠採用Unix域套接字方式，mysql.sock文件是服務器與本地客戶端進行通訊的Unix套接字文件，程序與mysqlserver處於同一臺機器，發起本地鏈接時可用。該文件由參數socket指定

mysql>show variables like 'socket'\G;

當MySQL實例啓動時，會將本身的進程ID寫入一個文件中—該文件即爲pid文件。該文件可由參數pid_file控制

mysql — The MySQL Command-Line Tool

mysqladmin — Client for Administering a MySQL Server

 

ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'db'

You may need to set up a root account for your MySQL database: In the terminal type: mysqladmin -u root password 'root' And then to invoke the MySQL client: mysql -h localhost -u root -p

mysqldump — A Database Backup Program

mysql啓動問題解決：

（一）mysqladmin: connect to server at 'localhost' failed
error: 'Access denied for user 'root'@'localhost' (using password: YES)'

沒法修改密碼

用 service mysqld stop

mysqld_safe --skip-grant-tables &

輸入 mysql -uroot -p 回車進入

>use mysql;

> update user set password=PASSWORD("newpass")where user="root";
 更改密碼爲 newpassord

新建用戶提示錯誤： 

insert into mysql.user(Host,User,Password) values("localhost","test",password("1234"));

 Field 'ssl_cipher' doesn't have a default value

那麼就不用insert了，換種方法：

GRANT USAGE ON *.* TO 'username'@'localhost' IDENTIFIED BY 'password' WITH GRANT OPTION;

「username」替換爲將要受權的用戶名，好比clientusr；

「password」替換爲clientusr設置的密碼；

locaohost能夠改成%，方便你從別的IP登陸。

而後對你建的用戶進行受權

GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP ON database.*  TO 'username'@'localhost' IDENTIFIED BY 'password';

GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'mima' WITH GRANT OPTION; //對全部ip受權

本語句中的權限根據實際須要肯定：

"tablename"替換爲受權訪問的數據表table名

"username"是步驟2受權用戶名

"password"是步驟2受權用戶的設置密碼

這樣就爲該用戶授予了對某數據表的SELECT, INSERT, UPDATE, DELETE, CAREATE, DROP權限。

四、生效受權，建立完畢

一句話便可：FLUSH PRIVILEGES;

 

特別提醒注意的一點是，新版（5.7）的mysql數據庫下的user表中已經沒有Password字段了

而是將加密後的用戶密碼存儲於authentication_string字段

> flush privileges; 更新權限

> quit 退出

service mysqld restart

mysql -uroot -p新密碼進入

 

（二）mysql start 或 mysqld start 啓動時 

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

（1）使用mysqld_safe &啓動

（1）因機器內存不足致使啓動失敗，將配置文件 etc/my.cnf 使用mysql-small.cnf （小內存）配置

或直接加以下配置至 my.cnf

key_buffer=16K

table_open_cache=4

query_cache_limit=256K

query_cache_size=4M

max_allowed_packet=1M

sort_buffer_size=64K

read_buffer_size=256K

thread_stack=64K

innodb_buffer_pool_size = 56M

 

（三）

ERROR 1044 (42000): Access denied for user ''@'localhost' to database 'db'

You may need to set up a root account for your MySQL database:

In the terminal type:

mysqladmin -u root password 'root password goes here'

And then to invoke the MySQL client:

mysql -h localhost -u root -p