php exec() - mysqldump creates an empty file

问题

I want to create a backup from a database, but I get only a blank file.

include('config.php');

$command = "mysqldump --opt -h ".$_host." -u ".$_user." -p ".$_pass." ".$_db." > test.sql";
exec($command);

echo "<br />".$command;

test.sql is created where the .php file is located.

Edit:

Note! I'm using XAMPP WINDOWS !

Solution:

Because I'm using a Windows Web Server (XAMPP), I needed to specify the path:

$command = 'd:\xampp\mysql\bin\mysqldump --opt -u '.$_user.' -p'.$_pass.' '.$_db.' > test.sql';

I removed the space between the -p and the pass. It looks like: -pMYPASSWORD
Replaced " with '

I think if you are using a Linux based web server, you don't have to specify the path for mysqldump.

Cheers! :-)

回答1:

Try this one:

$command = 'd:\xampp\mysql\bin\mysqldump --opt -u '.$_user.' -p'.$_pass.' '.$_db.' > test.sql 2>&1';

-its about permission issue.

回答2:

These are the parameters

-uROOT -pPASSWORD --databases DB --result-file=FILE.SQL

回答3:

If you look at the manual for exec the output goes to an array that is the second argument. That may be the source of the problem.

回答4:

You should remove the space between the -p and the password.

--opt isn't needed with recent versions of mysql.

Other than that, your syntax is correct so if it doesn't work with the -p fix, you should check the parameters and the produced command.

回答5:

Take the variables out of the quotes and remove --opt.

Also make sure that you are having unique file names

$backupfile = $dbname . date("Y-m-d-H-i-s") . '.sql';

$command = "D:\xampp\mysql\bin\mysqldump -u $_user -p$_pass $_db > $backupfile";

system($command);

回答6:

For those on Macs

I was battling this issue the entire evening today. Silly mistake: one needs to chmod the directory that you are dumping the file to.

I ran this which fixed the issue:

chmod -R 777 your_dump_directory/

回答7:

Try this:

$DBUSER="user";
$DBPASSWD="password";
$DATABASE="DBname";

$filename = "backup-" . date("d-m-Y") . ".sql";

$command = '"C:\Program Files\MySQL\MySQL Server 5.5\bin\mysqldump.exe" '.$DATABASE ." -u".$DBUSER ." -p".$DBPASSWD." > your_web_site/$filename";
passthru($command);

Change the route to the direction of the mysqldump.exe application of your computer.
Respect the " " inside the command.

Then force the download of the file:

if (file_exists("your_web_site/".$filename)) {
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="'.basename($filename).'"');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
readfile("your_web_site/".$filename);
exit;
}

Edit: You have to give permissions to the folder where you keep copies.

来源：https://stackoverflow.com/questions/12004292/php-exec-mysqldump-creates-an-empty-file

标签

php

mysql

exec

mysqldump