替换php读取的文件中的变量

Question

I have a small app I am working on that generates configuration files. Because it may be used to generate a few different variants of configurations, I gather the variable values from the user, and then read in a template configuration from a file. That file has the names of the variables in it (i.e. $ip_address) at the proper positions. I have set those variables in my php code before reading and the printing out the files. However, the variable names are printed out, not the values of the variables:

$hostname = $_POST['username'] . "_891";
$domain = $_POST['username'] . ".local";   
$routerFile = "891.txt";

$file_handle = fopen($routerFile, "r");
while (!feof($file_handle)) {
   $line = fgets($file_handle);
   print $line . "<br />";
}

Output example:

hostname $hostname
ip domain-name $domain

How do I get php to replace the variables names with their stored values?

Answer 1

I would go this way:

Create a template with hostname = <?php echo $hostname; ?> lines like so:

hostname <?php echo $hostname; ?>
ip domain-name <?php echo $domain; ?>

Then in PHP creating a template You would do:

ob_start();
include_once($routerFile);
$file_output = ob_get_clean();

Now You have the file template filled with the appropriate variables and You can save that file:

file_put_contents('my_new_router_file.txt', $file_output);

And You should be done.