Mysqdump has been backed up to 0 bytes.

Mysqdump has been backed up to 0 bytes. Php backup mysql:

Method 1:
"C: \ Program Files \ MySQL Server 5.5 \ bin \ mysqldump-uroot-hlocalhost-proot aa> C: \ www \ aa \ admin \ bak \\". $ _ POST [B _name];
Exec ($ mysqlstr); the backup is 0 bytes.
Method 2:
"C: \ Program Files \ MySQL Server 5.5 \ bin \ mysqldump-uroot-hlocalhost-proot aa> .. bak"; the backup is still 0 bytes,
How to write the statement, please.

Reply to discussion (solution)

Run
C: \ Program Files \ MySQL Server 5.5 \ bin> mysqldump-uroot-proot-hl
Ocalhost aa> C: \ www \ aa \ admin \ bak \ 20130327. SQL
The result is no problem, but rising prompts to intercept it, and others are normal.

First, mark One. I'll study it.

C:\Program Files\MySQL\MySQL Server 5.5\bin\mysqldump -u root -proot aa  > C:\www\aa\admin\bak\20130327.sql

-Add a space in the center of u root.

The code for successful testing is as follows:

exec('e:\xampp\mysql\bin\mysqldump -unowphp -pnowphp examples>e:\\back1253.sql')

Thank you for solving the problem. The reason is that the mysql directory cannot contain spaces. after the test is completed, mark will also add points.

Directory where mysqldump is located