4.5.1.3 mysql Logging

On Unix, the mysql client logs statements executed interactively to a history file. By default, this file is named .mysql_history in your home directory. To specify a different file, set the value of the MYSQL_HISTFILE environment variable.

How Logging Occurs

Statement logging occurs as follows:

• Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the --batch or --execute option.

• mysql logs each nonempty statement line individually.

• If a statement spans multiple lines (not including the terminating delimiter), mysql concatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter.

Consequently, an input statement that spans multiple lines can be logged twice. Consider this input:

mysql> SELECT
    -> 'Today is'
    -> ,
    -> CURDATE()
    -> ;

In this case, mysql logs the “SELECT”, “'Today is'”, “,”, “CURDATE()”, and “;” lines as it reads them. It also logs the complete statement, after mapping SELECT\n'Today is'\n,\nCURDATE() to SELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output:

SELECT
'Today is'
,
CURDATE()
;
SELECT 'Today is' , CURDATE();

Controlling the History File

The .mysql_history file should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. See Section 6.1.2.1, “End-User Guidelines for Password Security”.

If you do not want to maintain a history file, first remove .mysql_history if it exists. Then use either of the following techniques to prevent it from being created again:

• Set the MYSQL_HISTFILE environment variable to /dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files.

• Create .mysql_history as a symbolic link to /dev/null; this need be done only once:

  shell> ln -s /dev/null $HOME/.mysql_history