LAMP Tips!

MySQL / General – Dump all databases

LampTips — Sun, 05 Feb 2012 07:54:10 +0000

Sometimes, you need to do a full dump of your databases to import to another server.

First, make sure you are taking no writes to the database (unless EVERY table is InnoDB). If the former is true:

mysqldump -uUsername -p -A > dump.sql

If the latter is true (all tables InnoDB, except of course the mysql DB):

mysqldump -uUser -pPass --single-transaction -A > dump.sql

MySQL/General – Database + Index + Total Size

LampTips — Mon, 30 Jan 2012 06:56:10 +0000

Ever need to find the Data+Index size for your DB?
Try this query:

SELECT DBName,
  CONCAT(LPAD(FORMAT(SDSize/POWER(1024,pw),3),17,' '),' ',SUBSTR(' KMGTP',pw+1,1),'B') "Data Size",
  CONCAT(LPAD(FORMAT(SXSize/POWER(1024,pw),3),17,' '),' ',SUBSTR(' KMGTP',pw+1,1),'B') "Index Size",
  CONCAT(LPAD(FORMAT(STSize/POWER(1024,pw),3),17,' '),' ',SUBSTR(' KMGTP',pw+1,1),'B') "Total Size"
FROM (
  SELECT IFNULL(DB,'All Databases') DBName,
  SUM(DSize) SDSize,
  SUM(XSize) SXSize,
  SUM(TSize) STSize
  FROM (
    SELECT table_schema DB,
      data_length DSize,
      index_length XSize,
      data_length+index_length TSize
    FROM information_schema.tables
    WHERE table_schema NOT IN ('mysql','information_schema','performance_schema')) AAA
    GROUP BY DB WITH ROLLUP
) AA,
(SELECT 2 pw) BB
ORDER BY (SDSize+SXSize);

Linux/General – tar – Too many arguments

LampTips — Mon, 30 Jan 2012 06:40:57 +0000

Occasionally, when working in directories with large numbers of files and/or directories contained within them, you will get an error stating: Too many arguments.

This is not an error from the application. Rather, it is an error from the shell erroring on ARG_MAX limit reached.
There are a few ways to get around this, none of them are particularly elegant:

Using tar inside of a directory with too many files.

find . -print | tar -cvzf archive.tar.gz --files-from -

Using cp to move files, but too many files to work with:

for x in $( ls ); do cp $x /new/location; done

These are just some examples of ways to get around that problem. As a rule of thumb, try to keep the number of files in any given directory to < 1024.

MySQL/Security – Cleaning up post-install

LampTips — Mon, 30 Jan 2012 04:42:45 +0000

A default install of MySQL has anonymous users and root users with access via ‘%’ (all outside hosts) and a generally useless ‘test’ database.
The best method to do this is to execute the following at the shell prompt:

mysql_secure_installation

If this feature is not available, simply execute the following set of queries in MySQL:

DROP DATABASE `test`;
DELETE FROM `mysql`.`user` WHERE `User` = '';
DELETE FROM `mysql`.`user` WHERE `User` = 'root' AND `Host` != 'localhost';
FLUSH PRIVILEGES;

Apache/Security – Hide Apache Version Number

LampTips — Mon, 30 Jan 2012 04:38:16 +0000

Sometimes, you may like a bit of security-through-obscurity. Some PCI providers even require this.
You can disable the display of the Apache version by adding the following to your httpd.conf (Generally in /etc/httpd/conf):

ServerSignature Off
ServerTokens Prod

Apache/PCI – Disable Weak Cipher and older TLS Support

LampTips — Sun, 29 Jan 2012 11:13:25 +0000

PCI compliance tests require you to disable weak ciphers and older TLS support.
You can do that by adding the following to your httpd.conf (Generally under /etc/httpd/conf/):

SSLProtocol all -SSLv2
SSLCipherSuite ALL:!ADH:!EXPORT56:+HIGH:+MEDIUM:-SSLv2:-RC4:+EXP

Apache/PCI – Disable TRACE Method

LampTips — Sun, 29 Jan 2012 11:08:31 +0000

Some PCI tests require that you disable the Apache TRACE method as this can reveal sensitive information about the server.
Doing so is very simple! Add the following to your httpd.conf file (Generally in /etc/httpd/conf/):

TraceEnable off