從更新日誌文件中實時地逐行讀取

Question

我有一個日誌文件，我將數據寫入php文件。這是該代碼：這是工作

$filename='/var/log/siawa/dashboard/iot.log'; 

$source_file = fopen($filename, "r") or die("Couldn't open $filename"); 

while (!feof($source_file)) { 
    $buffer = fgets($source_file, 4096); // use a buffer of 4KB 
    $buffer = str_replace($old,$new,$buffer); 
    echo $buffer. "<br />" . "\n"; 
} 

，但我想，一旦它被寫在原始日誌文件每隔10秒鐘後說，以更新PHP的日誌數據。怎麼做。

Answer 1

您需要閱讀無限循環中的文件內容while(true)。我會通過代碼評論來解釋。

// read.php 
<?php 

// Last read position 
$last = 0; 

// Path to the updating log file 
$file = 'log.txt'; 

while (true) { 
    // PHP caches file information in order to provide faster 
    // performance; In order to read the new filesize, we need 
    // to flush this cache. 
    clearstatcache(false, $file); 

    // Get the current size of file 
    $current = filesize($file); 

    // Reseted the file? 
    if ($current < $last) { 
     $last = $current; 
    } 
    // If there's new content in the file 
    elseif ($current > $last) { 
     // Open the file in read mode 
     $fp = fopen($file, 'r'); 

     // Set the file position indicator to the last position 
     fseek($fp, $last); 

     // While not reached the end of the file 
     while (! feof($fp)) { 
      // Read a line and print 
      print fgets($fp); 
     } 

     // Store the current position of the file for the next pass 
     $last = ftell($fp); 

     // Close the file pointer 
     fclose($fp); 
    } 
} 

要進行測試，打開一個終端窗口，併發出：

while true; do echo `date` >> log.txt; sleep 1; done 

這將當前日期時間字符串追加到每個單獨第二的文件。現在打開另一個終端併發出php read.php以查看是否正在實時讀取文件。它會輸出這樣的事情：

Wed Dec 28 18:01:12 IRST 2016 
Wed Dec 28 18:01:13 IRST 2016 
Wed Dec 28 18:01:14 IRST 2016 
Wed Dec 28 18:01:15 IRST 2016 
Wed Dec 28 18:01:16 IRST 2016 
Wed Dec 28 18:01:17 IRST 2016 
Wed Dec 28 18:01:18 IRST 2016 
# Keeps updating... 

如果你傾向於通過HTTP服務這一點，你需要打印讀取緩衝區後添加ob_flush()電話：

// While not reached the end of the file 
while (! feof($fp)) { 
    print fgets($fp) . '<br>'; 

    // Flush the output cache 
    ob_flush(); 
}