Basically it works like this

exec('c:\\windows\\system32\cmd.exe /C "c:\\my\\commando.exe --arg"');

All the backslashes have to be escaped. Also you'll need to use escapeshellarg() 
if you pass something dynamically or if there are spaces in the path. Also it's 
better to put the suffix as well, like command.exe .

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

and actually it's not a bug :)

I tried with this ,Its not working, can you please check my code and guide me
exec('c:\\windows\\system32\cmd.exe /C "C:\\Program 
Files\\PostgreSQL\\9.0\\bin\\pg_dump.exe -U postgres -h localhost -p 5432  
recipedb1 >  C:\\TEMP\\new.sql"');

You have to shellescapearg() the path to 'program files', something like this 
works perfectly

$cmd = escapeshellarg('c:\\Program Files\\7-Zip\\7z.exe');
exec("c:\\windows\\system32\\cmd.exe /C \"$cmd -h\"", $out);
print_r($out);

I tried with

$cmd = escapeshellarg('pg_dump -U postgres -h localhost -p 5432  recipedb1 >  
C:\TEMP\dump123s.sql');
exec("c:\\windows\\system32\\cmd.exe /C \"$cmd -h\"", $out);
print_r($out);

and

$cmd = escapeshellarg('pg_dump -U postgres -h localhost -p 5432  recipedb1 >  
C:\TEMP\dump123s.sql');
exec("c:\\windows\\system32\\cmd.exe /C \"$cmd -h\"", $out);
print_r($out);

and 


$cmd = escapeshellarg('C:\\Program Files\\PostgreSQL\\9.0\\bin\\pg_dump.exe');
exec("c:\\windows\\system32\\cmd.exe /C \"$cmd -U postgres -h localhost -p 5432  
recipedb1 >  C:\\TEMP\\new.sql\"", $out);
print_r($out);

But there is no output, empty file is created, But database dump is not 
exported, Also I delete the file, Its says cannot delete file, Its used by 
cmd.exe

Of course the out is empty as it's redirected to a file. I'd remove the stdout 
redirection and see what the out is, that would bring you forward. But please, use 
the support channel, this bugtracker is really for the PHP bugs.