Accessing /var/log files from php

Question

I want to use PHP to show some syslog info on a web page to remote monitor my home linux box. I.e. some stuff filtered with grep out of /var/log/daemon.log

<?php
  $output = `grep ddclient /var/log/daemon.log`;
  echo "<pre>$output</pre>";
?>

Now the file /var/log/daemon.log is owned by root and the PHP user (www-data) has no access. So obviously the above returns empty.

What's the solution?

Thanks, Gert

Barmar · Accepted Answer · 2013-05-31 19:33:40Z

2

This is a variant of Puggan Se's setuid solution, but a bit better IMHO.

Create a grep_ddclient.sh shell script, containing:

#!/bin/sh
grep ddclient /var/log/daemon.log

Then add the following to /etc/sudoers:

apache ALL=NOPASSWD: /path/to/grep_ddclient.sh

Then run sudo /path/to/grep_ddclient.sh from PHP

answered May 31, 2013 at 19:33

Barmar

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Puggan Se · Accepted Answer · 2013-05-31 19:12:46Z

1

Alt 1: change read access of the file /var/log/daemon.log so apache can read it.

Alt 2: put grep ddclient /var/log/daemon.log in a shell file, and then activate the SETUID flag on it, and give apache the right to execute it

chown root:apache grep_ddclient.sh
chmod 550 grep_ddclient.sh
chmod +s grep_ddclient.sh

and then run grep_ddclient.sh from php

answered May 31, 2013 at 19:12

Puggan Se

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