How to take input from user and save that into other file - php

Question

I want to take input from user and save that into other file while keepping current data.
I want to take below details from user
server type : cpanel , FTP , windows , other (drop down)
Hostname
Username
Password
And save that in backup.php file. In backup php file I already have format
<?php
include xmlapi.php
$hostname= "";
$username = "";
$password = " ";
?>
I want details provided by user in this file. I can generare php file to ask these details but not sure how to insert data in backup.php while keeping existing data
can I get some help on it ?
Thanks

Answer 1

Using this config :
<?php
include xmlapi.php
$hostname = "";
$username = "";
$password = "";
?>
This will write user submitted data to that file :
<?php
$filename = "backup.php";
$user_data = $_POST; // contains $_POST['hostname'], $_POST['username'], etc
if(file_exists($filename))
{
$error_line = '';
foreach ($user_data as $config_name => $new_value)
{
$out = '';
$file = fopen($filename,'r+');
while(!feof($file))
{
$line = fgets($file);
$pattern_open = preg_match('/\$'.$config_name.'[ ]*=\s/i', $line, $matches_open);
$pattern_close = preg_match('/;.*\n/i', $line, $matches_close);
$out .= $matches_open != FALSE ? $matches_open[0] . "'" . $new_value . "'" . $matches_close[0] : $line;
}
fclose($file);
if (!file_put_contents($filename, $out))
{
if ($config_name === key($user_data))
{
$error_line .= "$config_name";
}
else
{
$error_line .= "$config_name, ";
}
}
}
if ($error_line != NULL)
{
echo 'Error at line : ' . $error_line;
}
else
{
echo 'Config saved';
}
}
else
{
echo 'File not found!';
}