strace 解决 mysql 连接数据库总是定位/tmp/mysql.sock的问题

Posted 2022-04-07

查看mysqld和mysql默认读取my.cnf的顺序

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mysql --help --verbose | grep ‘my.cnf‘
order of preference, my.cnf, $MYSQL_TCP_PORT,
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf

mysqld --verbose --help | grep ‘my.cnf‘
/etc/my.cnf /etc/mysql/my.cnf /usr/local/mysql/etc/my.cnf ~/.my.cnf
my.cnf, $MYSQL_TCP_PORT, /etc/services, built-in default
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报错的表现

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mysql
ERROR 2002 (HY000): Can‘t connect to local MySQL server through socket ‘/tmp/mysql.sock‘ (2)
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stace mysql 命令的执行过程

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strace /usr/local/mysql/bin/mysql
execve("/usr/local/mysql/bin/mysql", ["/usr/local/mysql/bin/mysql"], [/ 21 vars /]) = 0
= 0
stat("/etc/my.cnf", 0x7ffca8678640) = -1 ENOENT (No such file or directory)
stat("/etc/mysql/my.cnf", 0x7ffca8678640) = -1 ENOENT (No such file or directory)
stat("/usr/local/mysql/etc/my.cnf", st_mode=S_IFREG|0644, st_size=3816, ...) = 0
open("/usr/local/mysql/etc/my.cnf", O_RDONLY) = 3
fstat(3, st_mode=S_IFREG|0644, st_size=3816, ...) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb9595ef000
read(3, "# For advice on how to change se"..., 4096) = 3816
read(3, "", 4096) = 0
close(3) = 0
munmap(0x7fb9595ef000, 4096) = 0
stat("/root/.my.cnf", 0x7ffca8678640) = -1 ENOENT (No such file or directory)
stat("/root/.mylogin.cnf", st_mode=S_IFREG|0600, st_size=504, ...) = 0
open("/root/.mylogin.cnf", O_RDONLY) = 3
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删除.mylogin.cnf文件

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rm /root/.mylogin.cnf
rm: remove regular file ‘/root/.mylogin.cnf’? y
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再次登录正常

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#mysql
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Your MySQL connection id is 3
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