Display Message on redirect?

I'm making a page where you input info and click "Install" and then it goes to a file named "install_开发者_JS百科submit.php". I have it redirecting back to the form page when there is missing information display the message "Missing Information"!

this is my current code for "install_submit.php".

<?php
$dbname = $_POST['db_name'];
$dbuser = $_POST['db_user'];
$dbpass = $_POST['db_pass'];
$username = $_POST['username'];
$password = $_POST['password'];

if(empty($dbname) || empty($dbuser) || empty($dbpass) || empty($username) || empty($password))
{
header("Location: install.php");
Echo("Missing Information!");
}else{
Echo("Success!");
}
?>

Save it in a session and display it in your form location.

$_SESSION['error_message'] = "Missing Information!";

And in your form location:

<p class="errors"><?php if (!empty($_SESSION['error_message']) echo $_SESSION['error_message']; ?></p>

you can change the url in header and pass a parameter for example

header("Location: install.php?submit=false");

then in your "install_submit.php" you can get the info

if($_GET['submit'] == 'false') {
  echo("Missing Information!"); 
}

You need to use a session variable, like so:

session_start();
if(empty($dbname) || empty($dbuser) || empty($dbpass) || empty($username) || empty($password))
{
    $_SESSION["error_message"] = "Missing Information!";
    header("Location: install.php");
}else{
    unset($_SESSION["error_message"]);
    echo "Success!";
}

Then, on install.php reference the session variable somewhere like this:

<?php 
if (isset($_SESSION["error_message"])) {
    echo $_SESSION["error_message"];
}
?>

Don't do a redirect and don't use a separate url for processing. Handle the form submit on the same page. You don't want your user to provide all the information again.

You could redirect to install.php?error=true&db_name=...&db_user=... but it's just more complicated.

After you redirect, you will no longer be able to output from the current page. This is why your echo("missing information!"); does not do anything at the moment.

You could try setting the error message in a session, and then check if the error-session is populated on the form page:

session_start();
$_SESSION['errmsg'] = "Missing information!";
header("Location: install.php");

and then in your install.php:

session_start();
if(isset($_SESSION['errmsg'])) {
echo $_SESSION['errmsg'];
unset($_SESSION['errmsg']);
}