How to change a line from a text file (PHP)

Question

Text file(text.txt):

#Minecraft server properties
#Tue Sep 23 18:07:26 CEST 2014
generator-settings=
op-permission-level=4
allow-nether=true
level-name=world
enable-query=true
allow-flight=false
announce-player-achievements=true
server-port=25565
query.port=25565
level-type=DEFAULT
enable-rcon=false
force-gamemode=false
level-seed=
server-ip=
max-build-height=256

How to replace the value of some line, such as these:

server-port=25565

Replace with:

server-port=25585

But no to find 'server-port=25565' and replace with 'server-port=25585' It is found that the lines in which the server port and to allocate a value that needs to be replaced.

Example:

<?php
    $myfile = fopen("text.txt", "r") or die("Unable to open file!");
    ...
    fclose($myfile);
?>

EDIT: And when finded this and saved replace the text file.

Answer 1

Since your format looks suspiciously like a PHP configuration file (.ini), why not using the parse_ini_file function?

$ini = parse_ini_file("text.txt");
echo "<pre>".print_r($ini,TRUE)."</pre>";

or

echo $ini["server-port"];

Change it:

$ini["server-port"] = 25585;

Save again your .txt file with:

$f = fopen("text.txt","w");
foreach($ini as $k=>$v) {
   fwrite($f,$k."=".$v.PHP_EOL);
}
fclose($f);

You may need to change your # comments symbol though with ;

UPDATE

$lines = file("text.txt",FILE_IGNORE_NEW_LINES);
// modify
foreach($lines as &$line) {
   $val = explode("=",$line);
   if ($val[0]=="server-port") {
      $val[1] = "25585";
      $line = implode("=",$val);
   }
}
unset($line);

// save again
$f = fopen("text.txt","w");
foreach($lines as $line) {
   fwrite($f,$line.PHP_EOL);
}
fclose($f);