How to read only 5 last line of the text file in PHP?

Question

I have a file named file.txt which is update by adding lines to it.

I am reading it by this code:

$fp = fopen(\"file.txt\", \"r\");
$da         


        

Answer 1

Least amount of ram, and outputs well. I agree with Paul Dixon...

$lines=array();
$fp = fopen("userlog.txt", "r");
while(!feof($fp))
{
 $line = fgets($fp, 4096);
 array_push($lines, $line);
 if (count($lines)>25)
   array_shift($lines);
}
fclose($fp);

while ($a <= 10) {
$a++;
echo "<br>".$lines[$a];
}

Answer 2

If your lines are separated by a CR or LF you would try exploding your $data variable:

$lines = explode("\n", $data);

$lines should end up being an array and you can work out the number of records using sizeof() and just get the last 5.

Answer 3

This is a common interview question. Here's what I wrote last year when I was asked this question. Remember that code you get on Stack Overflow is licensed with the Creative Commons Share-Alike with attribution required.

<?php

/**
 * Demonstrate an efficient way to search the last 100 lines of a file
 * containing roughly ten million lines for a sample string. This should
 * function without having to process each line of the file (and without making
 * use of the “tail” command or any external system commands). 
 * Attribution: https://stackoverflow.com/a/2961731/3389585
 */

$filename = '/opt/local/apache2/logs/karwin-access_log';
$searchString = 'index.php';
$numLines = 100;
$maxLineLength = 200;

$fp = fopen($filename, 'r');

$data = fseek($fp, -($numLines * $maxLineLength), SEEK_END);

$lines = array();
while (!feof($fp)) {
  $lines[] = fgets($fp);
}

$c = count($lines);
$i = $c >= $numLines? $c-$numLines: 0;
for (; $i<$c; ++$i) {
  if ($pos = strpos($lines[$i], $searchString)) {
    echo $lines[$i];
  }
}

This solution does make an assumption about the maximum line length. The interviewer asked me how I would solve the problem if I couldn't make that assumption, and had to accommodate lines that were potentially longer than any max length I chose.

I told him that any software project has to make certain assumptions, but I could test if $c was less than the desired number of lines, and if it isn't, fseek() back further incrementally (doubling each time) until we do get enough lines.

Answer 4

$dosya = "../dosya.txt";
$array = explode("\n", file_get_contents($dosya));
$reversed = array_reverse($array);
for($x = 0; $x < 6; $x++) 
{
    echo $reversed[$x];
}

Answer 5

If you're on a linux system you could do this:

$lines = `tail -5 /path/to/file.txt`;

Otherwise you'll have to count lines and take the last 5, something like:

$all_lines = file('file.txt');
$last_5 = array_slice($all_lines , -5);

Answer 6

You can use my small helper library (2 functions)

https://github.com/jasir/file-helpers

Then just use:

//read last 5 lines
$lines = \jasir\FileHelpers\FileHelpers::readLastLines($pathToFile, 5);