After much searching I saw nothing. I even started at the / directory and was coming up with nothing. So naturally I went right to the log files. Believe it or not, it was not in the log files that I discovered where the problem was. Of course I thought I should share this experience with ghacks in order to illustrate how troubleshooting a Linux machine can go.

After the futile manual file search for files I went to the logs. The first log I went to (which is the first log I always turn to) dmesg which prints the message buffer from the kernel. To view this you just type dmesg at the terminal window. This was my first strike as the kernel buffer knew nothing of my capacity drive.

My next step was to head on over to /var/log and take a peek around any of the log files that might offer up a clue as to why my hard drive was maxed out. My instincts always take me to /var/log/messages first. This particular log file keeps track of general system information regarding boot up, networking. Another strike.

At this point I realized I had to take a break and clear some space because the warnings wouldn’t stop. I doubled checked to make sure the reports were correct by issuing the command:

df -h

which confirmed that /dev/sda1 was at 100% usage. I managed to free up a couple of gigs of space by deleting some torrents. The errors went away and I could continue working.

My next step was to check the size of my proxy logs and Dansguardian logs. I had to move both systems over to my main desktop and had a feeling those logs needed to be rotated. I was right, but it didn’t solve my problem. The tiny prox logs weren’t huge (by any stretch of the imagination), but they were many. So I deleted the older logs and moved on.

I was running out of log files to check and nothing had given me any idea what was going on.

Search and destroy

It was time to go back to the search method. But instead of using the manual method (how long would it take to weed through the ENTIRE Linux file system – I didn’t want to know) I opted to employ a little help thanks to the find command. The find command allows you to add switches to your search to indicate file size. In my case I wanted to first see if there were any files larger than 100 MB in size. To do this I will issue the command:

find / -size +1000000k -print0 | xargs -0 ls -l

as either root or using sudo. What this command does is tell find to search for files > 1000MB and send them to the standard output (that’s basically the terminal window), and pipe them to xargs so that you can see the detailed list (using “-l” of ls).  Because I was starting at the root directory, I knew this would take some time.

It did. But after some time I discovered five files that were each 12 gigs in size in /var/cache/. These files were from a backup program I was working with and forgot to disable. So once a week my entire /home directory was being backed up. I deleted the files (recovering sixty gigs of space) and disabled the backup program. Problem solved.

Final thoughts

There are times when even the best logging system available will not tell you what you need to know. At those times you have to employ your best sluething techniques. Fortunately the Linux operating system encourages these types of administration tricks.

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Webmin arrived on the scene in 1997 and pretty much blew away the competition. Webmin is truly a one-stop shop for Linux configuration. It’s modular so you can add and remove modules as they are needed. Webmin can configure your system, servers, networking, hardware, clusters, you name it!

Even though Webmin is a web-based utility, it does not require a server to be installed or running. Webmin contains its own built-in server so you will not need Apache running. Webmin does have to be running in order to log in.

The easiest way to install Webmin is to open up your Add/Remove Software utility, do a search for webmin, and install it. Or you can go to the Webmin Site, download the the appropriate binary and let your package manager do the work for you. If you are wanting to install Webmin on a headless server you can do the following:

• Secure shell to your server
• Download the correct installation file using the wget command.
• Issue the command to install Webmin (such as rpm -ivh webmind-XXX.rpm (where XXX is the release number)

After the installation is complete you may have to start Webmin manually (the rpm installation starts the server for you). To start Webmin you will issue the command:

/etc/rc.d/init.d/webmin start

or

/etc/init.d/webmin start

Once you have started Webmin you log into it with with your browser by pointing it to:

http://IP_OR_DOMAIN:10000

Where IP_OR_DOMAIN is the IP address or the domain Webmin is installed on. If you are using it for local configuration you can point your browser to http://localhost:10000.

Webmin Main Page

As you can see, in the image to the left, the default Webmin page is very easy to navigate.Upon installation one of the first links you should click on this page is the Webmin link in the left navigation. When that menu expands you will see a number of entries, of which one is called Webmin Configuration.

The Webmin Configuration Page

Click on the Webmin Configuration option to reveal a number of possible choices. This section is very important because you will configure access, logging, certificates, categories, and a number of other critical features.

Make sure, however, when you make any changes to Webmin that restart the Webmin server. You can restart Webmin by clicking the Restart Webmin button that is at the bottom of the Webmin Configuration page.

Controlling Webmin

In the same area of the restart button there are a few other important options. If you know you are going to be using Webmin for all of your configuration needs you will want to make sure Webmin starts at boot.

Another important screen to visit, before you jump into various modules, is the Webmin Users screen. In this screen you can define groups and users and their various permissions for the Webmin system. Here you can define what modules a user or group has access to which can be very handy.

Once you get beyond Webmin basic configuration it is time to poke around the various modules. In later articles I will discuss some of the best of the Webmin modules.

Final Thoughts

Webmin is one of the most powerful administration tools available. If you haven’t experienced the power that is Webmin, install it now and see how much power you can have at your fingertips.

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