problem using system() function

[wassersohn]

Hi everyone!, I'm working with PHP and I am having some problems with the system function. I hope you can help me, please.

First of all, I'm using lampp (xampp for linux) and ubuntu 10.4. In my server, in a directory located in /opt/lampp/htdocs/iris I have a program made in c which I need to execute but, when I do it, system returns an error. I replace that program to another that only has a cout and it returns an error too so the program it's not the problem, is the way that I call it or something like that. I wrote exactly this:

$resultado = system("./main libor ./datos/n4/4.jpg ./datos/n4/4.cod ./datos/n4/4.err);
and in $resultado it returns false so the program fails. I have used umask(0) and chmod("nombrearchivoX",0777) in order to made all the archives that I'm using reachable for all type of users.

I executed the command that I'm passing to system manually and it all goes well!, and I'm in the right directory because I do a system("ls") and the program is there.

In the same directory, if I write an linux script and I use system("nameofthescript") it all goes well!! why not when I'm using a C++ compiled program??

Why can't I execute the program?, what am I doing wrong??

Thanks for all, all suggestions are welcome.

[sneakyimp]

If the program you are executing (in this case it looks like 'main') is not in the current working directory, your command is going to fail. Likewise, if those images and .cod and .err files are not in the current working directory, this command will fail. Try writing out the full paths to all of them:

define('PATH_TO_EXECUTABLE', '/opt/lampp/htdocs/iris/main'); // i'm not sure this is correct...you'll need to make sure it's what you want
define('PATH_TO_ARGS', '/some/full/path/to/datos/n4/');

$resultado = system(PATH_TO_EXECUTABLE . " libor " . PATH_TO_ARGS . "4.jpg " . PATH_TO_ARGS . "4.cod " . PATH_TO_ARGS . "4.err", $return_val);

if ($resultado === FALSE) { // note the triple equals sign so we can discern FALSE vs. the empty string
  echo 'COMMAND FAILED, false returned.  return_val:' . $return_val;
} else {
  echo 'command succeeded, return_val:' . $return_val;
}

You should read the docs on [man]system[/man] carefully and look at the examples. Make sure you use the optional 2nd argument to find the return value. If I'm not mistaken, the return value is zero when the command is successful. Try using it on a trivial command like "ls" or something and see what the return value is. A non-zero return value can be used to indicate error conditions.

I prefer to use [man]exec[/man] myself because it gives more control over the return value and the screen output.