PHP - Returning the last line in a file?

Question

I'm guessing it's fgets, but I can't find the specific syntax. I'm trying to read out (in a string I'm thinking is easier) the last line added to a log file.

Answer 1

@unique_stephen, your answer is flawed. PHP fseek returns 0 for success and -1 for failure. Storing the result in $begining (sic) and then later using it in a filter for ftell() isn't correct. If my reputation were higher I would have voted you down and left a comment. Here is a modified version of unique_stephen's function.

function readlastline($fileName)
{
    $fp = @fopen($fileName, "r");
    if (fseek($fp, 0) == -1)
        exit('Cannot seek to beginning of the file'); 
    $pos = -1;
    $t = " ";
    while ($t != "\n") {
        if (fseek($fp, $pos, SEEK_END) == -1)
            exit('Cannot seek to the end of the file');
        if (ftell($fp) == 0) {
            break;
        }
        $t = fgetc($fp);
        $pos = $pos - 1;
    }
    $t = fgets($fp);
    fclose($fp);
    return $t;
}

NOTE: PHP's fseek cannot manage to seek to the end of files larger than PHP_MAX_INT which is 32bit signed even on 64bit binaries.

Answer 2

You either have to read the file in line by line and save the last read line to get it.

Or if on unix/linux you might consider using the shell command tail

tail -n 1 filename

Answer 3

function seekLastLine($f) {
    $pos = -2;
    do {
        fseek($f, $pos--, SEEK_END);
        $ch = fgetc($f);
    } while ($ch != "\n");
}

-2 because last char can be \n

Answer 4

This one wont break for a 1 or 0 line file.

function readlastline($fileName)
{

       $fp = @fopen($fileName, "r");
       $begining = fseek($fp, 0);      
       $pos = -1;
       $t = " ";
       while ($t != "\n") {
             fseek($fp, $pos, SEEK_END);
             if(ftell($fp) == $begining){
              break;
             }
             $t = fgetc($fp);
             $pos = $pos - 1;
       }
       $t = fgets($fp);
       fclose($fp);
       return $t;
}

Answer 5

This looks like it is what you are looking for:

tekkie.flashbit.net: Tail functionality in PHP

It implements a function that uses fseek() with a negative index to roll up the file from the end. You can define how many lines you want to be returned.

The code also is available as a Gist on GitHub:

// full path to text file
define("TEXT_FILE", "/home/www/default-error.log");
// number of lines to read from the end of file
define("LINES_COUNT", 10);


function read_file($file, $lines) {
    //global $fsize;
    $handle = fopen($file, "r");
    $linecounter = $lines;
    $pos = -2;
    $beginning = false;
    $text = array();
    while ($linecounter > 0) {
        $t = " ";
        while ($t != "\n") {
            if(fseek($handle, $pos, SEEK_END) == -1) {
                $beginning = true; 
                break; 
            }
            $t = fgetc($handle);
            $pos --;
        }
        $linecounter --;
        if ($beginning) {
            rewind($handle);
        }
        $text[$lines-$linecounter-1] = fgets($handle);
        if ($beginning) break;
    }
    fclose ($handle);
    return array_reverse($text);
}

$fsize = round(filesize(TEXT_FILE)/1024/1024,2);

echo "<strong>".TEXT_FILE."</strong>\n\n";
echo "File size is {$fsize} megabytes\n\n";
echo "Last ".LINES_COUNT." lines of the file:\n\n";

$lines = read_file(TEXT_FILE, LINES_COUNT);
foreach ($lines as $line) {
    echo $line;
}

Answer 6

...Why just read the last line?

function readLines($fp, $num) {

    $line_count = 0; $line = ''; $pos = -1; $lines = array(); $c = '';

    while($line_count < $num) {
        $line = $c . $line; 
        fseek($fp, $pos--, SEEK_END);
        $c = fgetc($fp);
        if($c == "\n") { $line_count++; $lines[] = $line; $line = ''; $c = ''; }
    }   
    return $lines;
}

$filename = "content.txt";
$fp = @fopen($filename, "r");

print_r(readLines($fp, 2));

fclose($fp);