在PHP中滚动日志文件

Question

I'd like to write/read a rolling log file with PHP, where only the latest ~300 lines are stored/read and anything older is discarded. I'm not sure of the most efficient way of going about it - it needs to work fast as it's recording page hits on high traffic web sites.

Another PHP script will be regularly reading the log files and using the data for calculations. There are so many PHP file functions I'm confused as to where to start!

I don't think my hosting environment has access to commands such as tail or awk or similar, so a pure PHP solution is preferred. Any help appreciated!

Answer 1

You can use fopen: http://us3.php.net/manual/en/function.fopen.php

$mode = 'a+'; // opens the file with read/write access and sets the pointer to the end of the file
$handle = fopen ($filename, $mode);

Next you pump the file into an array and lob off everything except the last 300 lines.

If you are really interested in just keeping the file down to a certain size (you said ~300 lines) then you can use fseek http://us3.php.net/manual/en/function.fseek.php (From the manual):

<?php

$fp = fopen('somefile.txt', 'r');

// read some data
$data = fgets($fp, 4096);

// move back to the beginning of the file
// same as rewind($fp);
fseek($fp, 0);

?>