PHP - 返回文件的最后一行？

Question

我猜它是fgets,但我找不到具体的语法.我正在尝试读出(在字符串中我认为更容易)添加到日志文件的最后一行.

Answer 1

最简单的天真解决方案很简单:

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

但是,这会将整个文件加载到内存中.可能是一个问题(或不是).更好的解决方案是:

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

Answer 2

这看起来就像你在寻找:

tekkie.flashbit.net:PHP中的尾部功能

它实现了一个函数,该函数使用带有负索引的fseek()从末尾汇总文件.您可以定义要返回的行数.

该代码也可作为GitHub上的Gist:

// 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 3

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);

这样更好,因为它没有将完整的文件加载到内存中......

将YOUR_EOL设置为正确的行结尾,如果使用与脚本所在的OS的默认行结尾相同的行结尾,则可以使用常量PHP_EOL.

Answer 4

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

-2因为最后一个字符可以是\n