[mysql][error][solution] mysqldump creates empty file

18 Nov

Mysqldump command is used to take backup of the database. I faced an issue of empty backup file creation while running mysqldump command through php script. To debug this issue following steps are there:

1) Search mysqldump.exe or simply mysqldump in your WAMP, MAMP, LAMP, XAMPP etc directory.
2) First of all run the command in command line window (prompt). For instance mysqldump is residing at c:/lamp/bin/mysql/mysql5.5.8/bin, then from command prompt run

c:/lamp/bin/mysql/mysql5.5.8/bin/mysqldump > 

and the backup file will be created with following content
Usage: mysqldump [OPTIONS] database [tables]
OR     mysqldump [OPTIONS] –databases [OPTIONS] DB1 [DB2 DB3…]
OR     mysqldump [OPTIONS] –all-databases [OPTIONS]
For more options, use mysqldump –help
3) For taking backup of specific database some parameters are to be specified. Following command is there for taking backup of a specific database

--opt --host=$server --user=$user --password=$password 
$database_name > c:/lamp/backups/backupfilename.sql

Thus, you are done with taking backing from command line by using mysqldump command.

4) Same command is used there within php script for taking backup. Exec() is the php function used for running such commands. In a php file, paste the following code

exec("c:/lamp/bin/mysql/mysql5.5.8/bin/mysqldump --opt 
--host=$server --user=$user --password=$password 
$database_name > c:/lamp/backups/backupfilename.sql");

And the backup file will be created. To print the error code use

string exec ( string $command [, array &$output [, int &$return_var ]] )

and $return_var will have the error code.

5) Last step is to generalize this command for WAMP, MAMP, LAMP, XAMPP etc as per the location of mysqldump.exe file. Recursively trace all the directories within WAMP, MAMP, LAMP, XAMPP etc in order to find mysqldump.exe path.

Following code is there to do so.

function getDirectory( $path = '.'){

$ignore = array( 'cgi-bin', '.', '..','htdocs','www' );
$dh = @opendir( $path );
while( false !== ( $file = readdir( $dh ) ) ){
if( !in_array( $file, $ignore ) ){
if( is_dir( "$path/$file" ) ){
getDirectory( "$path/$file");
} else {
if($file == 'mysqldump')
$_SESSION['mysqldump_location'] = $path.'/';
closedir( $dh );
$_SESSION['mysqldump_location'] = '';
$src = $root."/backup.sql";
$cmd = $_SESSION['mysqldump_location']."mysqldump 
--opt --host=$host --user=$user --password=$pass $name >"

Thats it 🙂

1 Comment

Posted by on November 18, 2011 in mysql


Tags: , , , ,

One response to “[mysql][error][solution] mysqldump creates empty file

  1. tengotutto

    June 20, 2015 at 1:54 am

    For XAMPP

    exec(‘C:\xampp\mysql\bin\mysqldump –allow-keywords –opt -uroot -pPASS DATA_BASE > C:\xampp\mysql\bin\file.sql’);


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