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

Untested code, but should work:

$file = file("filename.txt");
for ($i = max(0, count($file)-6); $i < count($file); $i++) {
  echo $file[$i] . "\n";
}

Calling max will handle the file being less than 6 lines.

Answer 2

This doesn't use file() so it will be more efficient for huge files;

<?php
function read_backward_line($filename, $lines, $revers = false)
{
    $offset = -1;
    $c = '';
    $read = '';
    $i = 0;
    $fp = @fopen($filename, "r");
    while( $lines && fseek($fp, $offset, SEEK_END) >= 0 ) {
        $c = fgetc($fp);
        if($c == "\n" || $c == "\r"){
            $lines--;
            if( $revers ){
                $read[$i] = strrev($read[$i]);
                $i++;
            }
        }
        if( $revers ) $read[$i] .= $c;
        else $read .= $c;
        $offset--;
    }
    fclose ($fp);
    if( $revers ){
        if($read[$i] == "\n" || $read[$i] == "\r")
            array_pop($read);
        else $read[$i] = strrev($read[$i]);
        return implode('',$read);
    }
    return strrev(rtrim($read,"\n\r"));
}
//if $revers=false function return->
//line 1000: i am line of 1000
//line 1001: and i am line of 1001
//line 1002: and i am last line
//but if $revers=true function return->
//line 1002: and i am last line
//line 1001: and i am line of 1001
//line 1000: i am line of 1000
?>

Answer 3

I've tested this one. It works for me.

function getlast($filename,$linenum_to_read,$linelength){

   // this function takes 3 arguments;


   if (!$linelength){ $linelength = 600;}
$f = fopen($filename, 'r');
$linenum = filesize($filename)/$linelength;

    for ($i=1; $i<=($linenum-$linenum_to_read);$i++) {
    $data = fread($f,$linelength);
    }
echo "<pre>";       
    for ($j=1; $j<=$linenum_to_read+1;$j++) {
    echo fread($f,$linelength);
    }

echo "</pre><hr />The filesize is:".filesize("$filename");
}

getlast("file.txt",6,230);


?>

Answer 4

FAST

Here is FAST method for LARGE files with LOW memory cost - I develop Wallace Maxters answer (if you want to upvote - do it on his answer) by wrap his code inside handy function and add reverse feature

function readLastLines($filename, $num, $reverse = false)
{
    $file = new \SplFileObject($filename, 'r');
    $file->seek(PHP_INT_MAX);
    $last_line = $file->key();
    $lines = new \LimitIterator($file, $last_line - $num, $last_line);
    $arr = iterator_to_array($lines);
    if($reverse) $arr = array_reverse($arr);
    return implode('',$arr);
}

// use it by
$lines = readLastLines("file.txt", 5) // return string with 5 last lines

Answer 5

this is read last 10 line from text file

$data = array_slice(file('logs.txt'),10);

    foreach ($data as $line) 

    {

        echo $line."<br/>";
    }

Answer 6

For a large file, reading all the lines into an array with file() is a bit wasteful. Here's how you could read the file and maintain a buffer of the last 5 lines:

$lines=array();
$fp = fopen("file.txt", "r");
while(!feof($fp))
{
   $line = fgets($fp, 4096);
   array_push($lines, $line);
   if (count($lines)>5)
       array_shift($lines);
}
fclose($fp);

You could optimize this a bit more with some heuristics about likely line length by seeking to a position, say, approx 10 lines from the end, and going further back if that doesn't yield 5 lines. Here's a simple implementation which demonstrates that:

//how many lines?
$linecount=5;

//what's a typical line length?
$length=40;

//which file?
$file="test.txt";

//we double the offset factor on each iteration
//if our first guess at the file offset doesn't
//yield $linecount lines
$offset_factor=1;


$bytes=filesize($file);

$fp = fopen($file, "r") or die("Can't open $file");


$complete=false;
while (!$complete)
{
    //seek to a position close to end of file
    $offset = $linecount * $length * $offset_factor;
    fseek($fp, -$offset, SEEK_END);


    //we might seek mid-line, so read partial line
    //if our offset means we're reading the whole file, 
    //we don't skip...
    if ($offset<$bytes)
        fgets($fp);

    //read all following lines, store last x
    $lines=array();
    while(!feof($fp))
    {
        $line = fgets($fp);
        array_push($lines, $line);
        if (count($lines)>$linecount)
        {
            array_shift($lines);
            $complete=true;
        }
    }

    //if we read the whole file, we're done, even if we
    //don't have enough lines
    if ($offset>=$bytes)
        $complete=true;
    else
        $offset_factor*=2; //otherwise let's seek even further back

}
fclose($fp);

var_dump($lines);