如何禁止mysql记录历史命令？在执行 SQL命令时，mysql会将历史命令记录到~/.mysql_history文件中，因此我们用上下键就可以翻阅历史命令了。
也许某些特殊需要我们可能需要不让它记录这些历史命令，我们可以这样作：
[root@TestServer root]# ln -s /dev/null $HOME/.mysql_history
这个方法来自官方手册，下面是摘录：
On Unix, the mysql client writes a record of executed statements to a history file. By default, the history file is named .mysql_history and is created in your home directory. To specify a different file, set the value of the MYSQL_HISTFILE environment variable.
If you do not want to maintain a history file, first remove .mysql_history if it exists, and then use either of the following techniques:
Set the MYSQL_HISTFILE variable to /dev/null. To cause this setting to take effect each time you log in, put the setting in one of your shell’s startup files.
Create .mysql_history as a symbolic link to /dev/null:
shell> ln -s /dev/null $HOME/.mysql_history
You need do this only once.
