Trying to execute a C program from PHP and output to a web browser

Question

I have a C program which has been compiled to an executable. I can run this program from my console. I am trying to get the output from this program through my web browser so I am using the exec command in PHP. My PHP script works fine when I execute it from the command line, but when I call it over a browser I get no input. Here is my PHP program

    <?php
    echo  exec('/var/www/html/./readcard');
    ?>

The readcard program has 777 permissions. I am guess the issue is something to do with permissions?

Possible duplicate of Executing system command in PHP differs when using browser and when using command line — hakre
– hakre, Commented May 10, 2012 at 8:28

score 4 · Accepted Answer · 2012-05-09 15:40:48Z

4

You aren't capturing the output. The second argument to exec consists of an array to which the output lines will be placed.

<?php
$output=array();
$rv=0;
exec('/var/www/html/./readcard',$output,$rv);

if($rv!=0)
{
  die("readcard failed, got a return value of $rv\n");
}

foreach($output as $line)
{
  echo("<p>$line</p>\n");
}
?>

edited May 9, 2012 at 15:40

answered May 9, 2012 at 15:21

user554546

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3 Comments

user813813 Over a year ago

Hi Jack, thanks for that. Still the same. It outputs fine when I execute from the command line though.

user813813 Over a year ago

I think I have found the problem, my C program is calling a number of share objects and the operating system is preventing this. Trying to change the permissions on these objects.

petr Over a year ago

It could be a path problem - maybe it's not about the permission but the command running through apache just may not be able to see the shared objects

petr · Accepted Answer · 2012-05-09 15:20:43Z

1

You probably just echo the return code of the script, which is zero. You can either redirect the output to a file and then serve that from php, or pipe the output stream directly back to php code.

Try

<?php
    $output = array();
    exec('/var/www/html/./readcard', &$output);
?>

answered May 9, 2012 at 15:20

petr

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