How to stop .txt from getting too big PHP - php

Question

Hello,
I am making my first PHP using website and I have some things that I am writing to a log.txt. Everytime someone visits my website something gets written like this:
$dateTime = date('Y/m/d G:i:s');
$fh = fopen('log.txt', 'a');
fwrite($fh, 'Date / Time: '."".$dateTime ."\n\n");
fclose($fh);
Now I would like to know, how to set a max file size for my log.txt to stop it from getting too big. For example; it'll auto delete the oldest content "block" of let's say 6 lines long and replace it with the new one after the file has exceeded (for example) 500 lines.
I couldn't find this problem online so I am very curious to how I would do this.
If you have any questions please let me know and I hope you can help me with this problem!

Answer 1

Please try this code. I have tested it it works fine. I use \r\n for line break so that your text file is more readable.
$dateTime = date('Y/m/d G:i:s');
$fh = fopen('log.txt', 'a');
fwrite($fh, 'Date / Time: ' . "" . $dateTime . "\r\n");
fclose($fh);
now you check if the number of lines in the file exceed your limit, then remove the old lines from the top the the file and enter new line on the top, else just enter new line.
$block = 5; //block consist of 5 lines
$remove_blocks = 10; //remove the number of blocks
$remove = $block * $remove_blocks; //totle line to remove
$line_limit = 20;
$content = file_get_contents("log.txt");
$array = explode("\r\n", $content);
$count = count($array);
if ($count >= $line_limit) {
//Remove first few lines
$array = array_slice($array, $remove);
$new_data = implode("\r\n", $array);
$fh = fopen('log.txt', 'w');
fwrite($fh, $new_data . "\r\n");
fclose($fh);
} else {
$dateTime = date('Y/m/d G:i:s');
$fh = fopen('log.txt', 'a');
fwrite($fh, 'Date / Time: ' . "" . $dateTime . "\r\n");
fclose($fh);
}
Edit: put this code in a new test.php adn experiment with it
<?php
$block = 2; //block consist of 5 lines
$remove_blocks = 1; //remove the number of blocks
$remove = $block * $remove_blocks; //totle line to remove
$line_limit = 5;
$content = file_get_contents("log.txt");
$array = explode("\r\n", $content);
$array = array_slice($array, -1);
$count = count($array);
if ($count >= $line_limit) {
//Remove first few lines
$array = array_slice($array, $remove);
$new_data = implode("\r\n", $array);
$fh = fopen('log.txt', 'w');
fwrite($fh, $new_data . "\r\n");
fclose($fh);
$dateTime = date('Y/m/d G:i:s');
$fh = fopen('log.txt', 'a');
fwrite($fh, 'Date / Time: ' . "" . $dateTime . "\r\n");
fclose($fh);
} else {
$dateTime = date('Y/m/d G:i:s');
$fh = fopen('log.txt', 'a');
fwrite($fh, 'Date / Time: ' . "" . $dateTime . "\r\n");
fclose($fh);
}
?>

Answer 2

I suggest using "rotation log files" for this instead. Research on google about this. You will get some easy solutions for it.
For example How to configure logrotate with php logs

Answer 3

Here is an Example how to get Lines Count from File https://www.w3resource.com/php-exercises/php-basic-exercise-16.php
or you can try to get file Size:
if(filesize("log.txt") >= 5000){ echo "file to is large"; }
or
$content = file_get_contents("log.txt");
$array = explode("\n", $content);
$count = count($array);
if($count >= 500){
echo "file too large";
}

Answer 4

You can name the file with the date as a filename
So basically for each day you will have another file
$dateTime = date('Y/m/d G:i:s');
//The file will have the name log_2019-10-09.txt
$fh = fopen('log_'.date('Y-m-d').'.txt', 'a');
fwrite($fh, 'Date/Time: '."".$dateTime ."\n\n");
fclose($fh);