Live feed of an updating file

php jquery ajax file

10,196

With ajax. If you need cross-browser compatibility, replace the AJAX function I provided with one from a library like jQuery.

<html><head></head><body>
<div id="feed"></div>
<script type="text/javascript">
var refreshtime=10;
function tc()
{
asyncAjax("GET","myphpfile.php",Math.random(),display,{});
setTimeout(tc,refreshtime);
}
function display(xhr,cdat)
{
 if(xhr.readyState==4 && xhr.status==200)
 {
   document.getElementById("feed").innerHTML=xhr.responseText;
 }
}
function asyncAjax(method,url,qs,callback,callbackData)
{
    var xmlhttp=new XMLHttpRequest();
    //xmlhttp.cdat=callbackData;
    if(method=="GET")
    {
        url+="?"+qs;
    }
    var cb=callback;
    callback=function()
    {
        var xhr=xmlhttp;
        //xhr.cdat=callbackData;
        var cdat2=callbackData;
        cb(xhr,cdat2);
        return;
    }
    xmlhttp.open(method,url,true);
    xmlhttp.onreadystatechange=callback;
    if(method=="POST"){
            xmlhttp.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
            xmlhttp.send(qs);
    }
    else
    {
            xmlhttp.send(null);
    }
}
tc();
</script>
</body></html>

You will have to create a php file called myphpfile.php (or change the code above to reference the correct file) and put the following in it (as taken from your question):

<?php
$filename = '/home/duke/aa/servers/df/var/logs.log';  //about 500MB
$output = shell_exec('exec tail -n50 ' . $filename);  //only print last 50 lines
echo str_replace(PHP_EOL, '<br />', $output);         //add newlines
?>

10,196

Author by

dukevin

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Updated on June 08, 2022

Comments

dukevin almost 2 years
I have a php file that prints the last 50 lines of a txt file. However, this file gets appended every second and would like to view a "live feed" of the action. How can this be done? This is the code for the php file:
```
<?php
$filename = '/home/duke/aa/servers/df/var/logs.log';  //about 500MB
$output = shell_exec('exec tail -n50 ' . $filename);  //only print last 50 lines
echo str_replace(PHP_EOL, '<br />', $output);         //add newlines
?>
```
dukevin over 12 years

Was looking for an answer for a webrowser to point to this file and view the file in real time.
dukevin over 12 years

This looked promising, however I get a blank screen with this code
someone over 12 years

Did you replace myphpfile.php with the location of the file containing the code provided in your question?
dukevin over 12 years

Yes, I have. I have 2 files now, one with my short code above, and your code. Do I point my browser to your code or my code with a header like <script src="js.js">?
dukevin over 12 years

Hm, no luck. 209.141.56.244/test/query.html is where your code is, and 209.141.56.244/test/logtee.php is my file
someone over 12 years

Oh, I see the problem: you're missing a </div> after the <div id="feed">, and a </script> at the end. Try recopying my code again, I made a few changes.
someone over 12 years

Now you just have to change the filename again (myphpfile.php to logtee.php) and I think it'll work-- it's showing ton of requests to the non-existent myphpfile.php in my test.
dukevin over 12 years

Nevermind, it worked! Thanks very much. A million gold stars for you :)
jeroen over 12 years

+1 Although using ajax and a timeout function is the way to go, the php is going to be a lot more complicated to show just the new lines instead of the 50 last lines (to avoid doubles and / or missing entries).