CODEWITHSUNDEEP
phpsyntaxfreadfgets
waxical
waxical

Reputation: 3896

PHP - Returning the last line in a file?

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.

Upvotes: 22

Views: 58157

Answers (9)

Avinash.A.L
Avinash.A.L

Reputation: 11

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;
}

Upvotes: 1

Earnie
Earnie

Reputation: 111

@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.

Upvotes: 1

Tomalak
Tomalak

Reputation: 338158

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;
}

Upvotes: 15

constantined
constantined

Reputation: 51

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

-2 because last char can be \n

Upvotes: 5

Simon Harper
Simon Harper

Reputation: 29

...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);

Upvotes: 1

Kieran Hall
Kieran Hall

Reputation: 2627

If you want to read a file line by line the file function reads the contents of a file, line by line and returns each line as an element of an array.

So you could do something simple like:

$lines    = file('log.txt');
$lastLine = array_pop($lines);

Upvotes: 1

unique_stephen
unique_stephen

Reputation: 11

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;
}

Upvotes: 1

Jeroen Serpieters
Jeroen Serpieters

Reputation: 101

define('YOUR_EOL', "\n");
$fp = fopen('yourfile.txt', 'r');

$pos = -1; $line = ''; $c = '';
do {
    $line = $c . $line;
    fseek($fp, $pos--, SEEK_END);
    $c = fgetc($fp);
} while ($c != YOUR_EOL);

echo $line;

fclose($fp);

This is better, since it does not load the complete file into memory...

Set YOUR_EOL to your correct line endings, if you use the same line endings as the default line endings of the OS where your script resides, you could use the constant PHP_EOL.

Upvotes: 10

Matthew Scharley
Matthew Scharley

Reputation: 132254

The simplest naive solution is simply:

$file = "/path/to/file";
$data = file($file);
$line = $data[count($data)-1];

Though, this WILL load the whole file into memory. Possibly a problem (or not). A better solution is this:

$file = escapeshellarg($file); // for the security concious (should be everyone!)
$line = `tail -n 1 $file`;

Upvotes: 51

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