Reading a file and extracting data using a regex in PHP

Question

I am trying to echo out the names/paths of the files that are written in logfile.txt. For that, I use a regex to match everything before the first ocurrence of : and output it. I am reading the logfile.txt line by line:

<?php

$logfile = fopen("logfile.txt", "r");

if ($logfile) {
    while (($line = fgets($logfile)) !== false) {
        if (preg_match_all("/[^:]*/", $line, $matched)) {
            foreach ($matched as $val) {
                foreach ($val as $read) {
                    echo '<pre>'. $read . '</pre>';
                }
            }
        }
    }

    fclose($logfile);
} else {
    die("Unable to open file.");
}

?>

However, I get the entire contents of the file instead. The desired output would be:

/home/user/public_html/an-ordinary-shell.php
/home/user/public_html/content/execution-after-redirect.html
/home/user/public_html/paypal-gateway.html

Here is the content of logfile.txt:

-------------------------------------------------------------------------------

/home/user/public_html/an-ordinary-shell.php: Php.Trojan.PCT4-1 FOUND
/home/user/public_html/content/execution-after-redirect.html: {LDB}VT-malware33.UNOFFICIAL FOUND
/home/user/public_html/paypal-gateway.html: Html.Exploit.CVE.2015_6073

Extra question: How do I skip reading the first two lines (namely the dashes and emtpy line)?

use preg_match instead of preg_match_all

cmorrissey
– cmorrissey

2016-08-03 18:08:44 +00:00
Commented Aug 3, 2016 at 18:08 — cmorrissey
– cmorrissey, Commented Aug 3, 2016 at 18:08

Jan · Accepted Answer · 2016-08-03 18:20:15Z

3

Here you go:

<?php
# load it as a string
$data = @file("logfile.txt");

# data for this specific purpose
$data = <<< DATA
-------------------------------------------------------------------------------

/home/user/public_html/an-ordinary-shell.php: Php.Trojan.PCT4-1 FOUND
/home/user/public_html/content/execution-after-redirect.html: {LDB}VT-malware33.UNOFFICIAL FOUND
/home/user/public_html/paypal-gateway.html: Html.Exploit.CVE.2015_6073
DATA;

$regex = '~^(/[^:]+):~m';
# ^ - anchor it to the beginning
# / - a slash
# ([^:]+) capture at least anything NOT a colon
# turn on multiline mode with m

preg_match_all($regex, $data, $files);
print_r($files);
?>

It even skips both your lines, see a demo on ideone.com.

edited Aug 3, 2016 at 18:20

answered Aug 3, 2016 at 18:10

Jan

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6 Comments

McJohnson Over a year ago

I would've favored this answer but it outputs two arrays. The first one includes the : and the second starts without a slash before the names of the files.

Jan Over a year ago

Do you need the slashes? Updated the answer, loop over $files[1] to have your files. Additionally updated the ideone.com demo.

McJohnson Over a year ago

Let's say I do. Just because they are present in the file and I might need them for specific cases in the end. But I would also like to have just one array.

Jan Over a year ago

If you can be sure that there is always a colon (:) in every line with a slash at the beginning, you could as well use: $regex = '~^/[^:]+~m'; (no parentheses anymore) - bear in mind though that it will match much more if there's no colon (anything not a colon includes newline characters as well).

McJohnson Over a year ago

What purpose did the parentheses serve? And I accepted your answer, thank you.

|

Casimir et Hippolyte · Accepted Answer · 2016-08-03 19:20:16Z

3

preg_match_all returns all occurrences for the pattern. For the first line, it will return:

/home/user/public_html/an-ordinary-shell.php,
an empty string,
Php.Trojan.PCT4-1 FOUND and an other empty string

that don't contain :.

to obtain a single result, use preg_match, but to do that using explode should suffice.

To skip lines you don't want, you can for example build a generator function that gives only the good lines. You can also use a stream filter.

edited Aug 3, 2016 at 19:20

answered Aug 3, 2016 at 18:11

Casimir et Hippolyte

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1 Comment

McJohnson Over a year ago

Silly me. I forgot the difference between preg_match_all and preg_match. Did it with preg_match and explode. Thank you for your time. I would've accepted your answer as well but I can only accept one.

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