Question

Well you know I can use this:

<?php
$myfile = 'myfile.txt';
$command = "tac $myfile > /tmp/myfilereversed.txt";
exec($command);
$currentRow = 0;
$numRows = 20;  // stops after this number of rows
$handle = fopen("/tmp/myfilereversed.txt", "r");
while (!feof($handle) && $currentRow <= $numRows) {
   $currentRow++;
   $buffer = fgets($handle, 4096);
   echo $buffer."<br>";
}
fclose($handle);
?>

But doesn’t it copy the whole file to memory?

A better approach maybe fread() but it uses the bytes so might also not be the a good approach too.

My file can go into around 100MB so I want it.

Answer 1

If you’re already doing stuff on the command line, why not use tail directly:

$myfile = 'myfile.txt';
$command = "tail -20 $myfile";
$lines = explode("\n", shell_exec($command));

Not tested, but should work without PHP having to read the whole file.