shell_exec
  Execute command via shell and return the complete output as a string
  
 
  Description
  
   string shell_exec
    ( string $cmd
   )
  
  
 
  Parameters
  
   
    - 
     cmd
- 
      
       The command that will be executed.
       
 
 
  Return Values
  
   The output from the executed command or NULL if an error occurred or the
   command produces no output.
  
  Note: 
   
    This function can return NULL both when an error occurs or the program
    produces no output. It is not possible to detect execution failures using
    this function. exec should be used when access to the
    program exit code is required.
   
  
  
 
  Examples
  
   
    Example #1 A shell_exec example
    
<?php
$output = shell_exec('ls -lart');
echo "<pre>$output</pre>";
?>
     
    
  
  
 
  Notes
  Note: 
   
    This function is disabled when PHP is running in safe mode.