What’s an inode?

From linux-mag.com

In the electronic pages of Linux Magazine, file systems are commonly discussed. It’s a fact! In these discussions you might see the term “inode” used in reference to a file system. Fairly often people ask the question, “what is an inode?” so that they can understand the discussion (remember, there is no such thing as a bad question – at least for the most part).

To many people who read these storage articles this might seem like an elementary question but for many people just starting in Linux this concept may not be understood. Plus it’s always good to review the concept but let’s keep any comments civil and constructive (especially if they are directed at the author). Let me also state that I’m not a file system expert so please correct any misstatements but also please give references so people reading the comments can explore the topic.

File systems in general have two parts:

(1) the metadata or the “data” about the data, and

(2) the data itself. The first part, the metadata, may sound funny because it’s data about the data, but this is a very key component to file systems. It consists of information about the data. More precisely it includes information such as the name of the file, the date the file was modified, file owner, file permissions, etc. This type of information is key to a file system otherwise we just have a bunch of bits on the storage media that don’t mean much. Inodes store this metadata information and typically they also store information about where the data is located on the storage media. (more…)

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Monitorix

From monitorix.org

The Monitorix Project
Monitorix is a free, open source, lightweight system monitoring tool designed to monitor as many services and system resources as possible. It has been created to be used under production UNIX/Linux servers, but due to its simplicity and small size you may also use it on embedded devices as well.
It mainly consists of two programs; a collector called monitorix, a Perl daemon that it’s started automatically as any other system service, and a CGI called monitorix.cgi.

All of its development was initially created for monitoring Red Hat, Fedora and CentOS Linux systems, so this project was made keeping in mind these type of distributions. Today it runs on different GNU/Linux distributions and even in other UNIX systems, like FreeBSD.

Everytime monitorix is started it reads the configuration file from the path specified in the command line (using the -c option), and once checked, it creates the index.html file that will act as the Monitorix main page.

It also creates a file called $BASE_DIR/cgi-bin/monitorix.conf.path that includes the absolute path of the configuration file. This file will be read by monitorix.cgi to know the exact location of the configuration file. If by any reason monitorix.cgi is unable to locate this file, it will try two possible locations; /etc/monitorix.conf and /usr/local/etc/monitorix.conf. (more…)

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Disable bounce email on qmail

From savingneo.com

Hello All,
If you re having problems with bounce on qmail, if you re desperate about qmail getting crazy with thousands of email, then, let me tell you, that your quest ends here! The tools that will be used in this “kind of tutorial” are included right here :

qmHandle: a tool to handle and analyse your mail queue
qmhandle-1.3.2.tar.gz [15.06 KiB]

qmail-remove: a tool to clean your queue
qmail-remove-0.93.tar
qmail-remove-0.94.tar
qmail-remove-0.95.tar

Basic things you should know
[*]Where are the mail stored ?
Usually, for a mail like hello@mydomain.com you ll find the emails in /var/qmail/mailnames/mydomain.com/hello/Maildir/new or /cur. You can view their content with nano or vi or any text editor, and read them from your linux console, given they do not contains too much html gibberish.

[*]Where is the queue stored ?
The queue, is the as it sounds to be, “all the mails that have not been yet delivered” (delivered to a local user or to a remote user(not hosted on your mail server))

Delivering the queue to the local users is not a big process, but delivering it to remote destination, well, might give a hard time to qMail sometimes ! (as for any other mail system of course)
So, the queue is physically stored in folders within /var/qmail/queue/ Let’s not bother with the details of all folders in that path, for the moment, we dont care.

(more…)

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