<?php
$A = file_get_contents('iono.txt'); //Abrimos el file
$B = preg_split("|[\r\n]+|i", $A, -1, PREG_SPLIT_NO_EMPTY); //parseamos por salto de linea

$DTO = array();
foreach($B as $C){
$D = preg_split("|,|sU",$C,-1,PREG_SPLIT_NO_EMPTY); //parseamos por ,
if($D[4] == $_GET['cual']){ //verificamos si coincide con el campo cual pasado por GET (url.com/?cual=Sistemas)
$DTO['si'][] = array($D);
}else{
$DTO['no'][] = array($D);
}
}

echo '<pre>';print_r($DTO); //Mostramos el array en pantalla
?>

//Para mostrar los que coinciden
foreach($DTO['si'] as $T1){
echo $T1[0].' - '.$T1[1].'...';
}

//Para mostrar los que no coinciden
foreach($DTO['no'] as $T1){
echo $T1[0].' - '.$T1[1].'...';
}

<?php
// HTTP/1.1
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);

// HTTP/1.0
header("Pragma: no-cache");
?>

<?php
@session_start();

if($_GET['logout']=="1"){
$_SESSION['login'] = "";
@session_destroy();
}

if($_POST['user']!="" && $_POST['pass']!=""){
$_SESSION['login']=1;
}

if($_SESSION['login']!="1"){
echo '<form action="" method="POST">
User: <input type="text" name="user"><br/>
Pass: <input type="password" name="pass"><br/>
<input type="submit">
</form>';
die();
}

echo '<a href="?logout=1">LogOut</a>';
?>