Example of how to manage cron using PHP Rev #2

php-cronjob-setter.php

<?php
/*
Copyright 2017 Ananta
This is an example script of how to manage crontab using PHP
Yeah it's a messy script but it works :p
* Create the crontab.tmp.txt file first to use it. This script is unable to populate the file when running using a webserver like apache or nginx
*/

$user = exec('whoami');
$lastCrontab =shell_exec('crontab -u '.$user.' -l');


if(isset($_POST['submit'])){
    $cronjobs=$_POST['cronjobs'];
    //create tmp file
    file_put_contents('crontab.tmp.txt',$cronjobs."\n");
    //execute command and try to set new cronjobs
    echo shell_exec('crontab -u '.$user.' crontab.tmp.txt');
    echo "<a href=''>Go back</a>";
    //override tmp file
    file_put_contents('crontab.tmp.txt',null);
}else{
if(preg_match('/no crontab/i',$lastCrontab)){
    echo "No cronjob found for $user";
}else{
echo "<h2>Current cronjobs of $user</h2>";
    echo '<pre>';
    echo $lastCrontab;
    echo '</pre>';
}

echo"<h1>Create new cronjobs!</h1>";
echo "
<form action='' method='POST'>
<textarea cols=120 rows=20 name='cronjobs' placeholder='No cronjob were found! Create some'>$lastCrontab</textarea>
<br>
<button type='submit' name='submit'>Setup!</button>
</form>
";
}