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Debian

Monitoring Servers and Clients using Munin

Post date: April 4, 2006, 20:04 Category: Installing Views: 3000 Comments
Tutorial quote: "Munin" means "memory".

Munin the tool surveys all your computers and remembers what it saw. It presents all the information in in graphs through a web interface. Its emphasis is on plug and play capabilities. After completing a installation a high number of monitoring plugins will be playing with no more effort. Using Munin you can easily monitor the performance of your computers, networks, SANs, and quite possibly applications as well. It makes it easy to determine "what's different today" when a performance problem crops up. It makes it easy to see how you're doing capacity wise on all limited resources.

It uses the excellent RRDTool and is written in Perl. Munin has a master/node architecture in which the master connects to all the nodes at regular intervals and asks them for sdata. It then stores the data in RRD files, and (if needed) updates the graphs. One of the main goals has been ease of creating new plugins (graphs).
Linux

The Serial Console

Post date: April 14, 2005, 13:04 Category: Hardware Views: 3827 Comments
Tutorial quote: In these modern times, a hardworking admin might be tempted to turn her back on the Old Ways, and indulge in increasingly exotic methods of interfacing with servers: SSH over ethernet, USB, Firewire, wireless, infrared, KVM switches, VNC, VPN... next stop: direct neural implants.

There's one old timer that still has useful place in the admin's tool kit: the serial console. Sure, it's slow and funky. But there are times it can be a real lifesaver. When nothing else works, it's a direct pipeline into your system. It's simple and cheap. You don't need to install drivers or expansion cards, it's just there.

Administration via serial console is common in data centers. Just imagine the nightmare of trying to connect all those rack units to keyboards and displays. The cabling can be extended to a nice comfortable ops center (well, an ops center, anyway). (This Lantronix Console Manager is an example of the type of device used to administer these.)

There are a number of ways to make the physical connection. You can connect an external modem--the kind us old timers fondly refer to as "real" modems--and do remote administration via dialup. It couldn't be any simpler, just dial direct. Or grab a null modem cable, connect to a laptop or a nearby workstation, and you have an instant terminal.
RedHat

Ruby on Rails on Red Hat

Post date: November 27, 2006, 07:11 Category: Network Views: 8045 Comments
Tutorial quote: Ruby on Rails is an open source freely available web development framework. It's been quite popular--it won a Jolt "Web Development Tools" award last year, and some prominent Java developers have publically switched to Ruby on Rails. The buzz surrounding Rails is quite impressive--particularly when you consider that Rails had no Fortune 500 company to market it, unlike .NET or Java.

Rails is a Model View Controller (MVC) framework. As you can imagine from the name, applications written using Model View Controller frameworks have three main components: a model, which represents the data and associated logic; the view, which represents how a user interacts with the application; and the controller, which contains all of the business logic that drives the application. This is an artificial distinction, of course, but it is a powerful one.

You'll need Apache 2.0+ and MySQL installed on your Red Hat Linux computer to run these examples.
Linux

Creating Really Teensy ELF Executables for Linux

Post date: April 12, 2005, 18:04 Category: Miscellaneous Views: 3288 Comments
Tutorial quote: If you're a programmer who's become fed up with software bloat, then may you find herein the perfect antidote.

This document explores methods for squeezing excess bytes out of simple programs. (Of course, the more practical purpose of this document is to describe a few of the inner workings of the ELF file format and the Linux operating system. But hopefully you can also learn something about how to make really teensy ELF executables in the process.)

Please note that the information and examples given here are, for the most part, specific to ELF executables on a Linux platform running under an Intel-386 architecture. I imagine that a good bit of the information is applicable to other ELF-based Unices, but my experiences with such are too limited for me to say with certainty.

The assembly code that appears in this document is written for use with Nasm. (Besides being more appropriate for our needs, Nasm's syntax beats the hell out of AT&T syntax for anyone who learned x86 assembly language before learning to use Gas.) Nasm is freely available and extremely portable; see http://nasm.sourceforge.net/.

Please also note that if you aren't a little bit familiar with assembly code, you may find parts of this document sort of hard to follow.
Linux

Linux Web Filtering in 7 steps

Post date: April 12, 2005, 18:04 Category: Network Views: 4652 Comments
Tutorial quote: How to install a transparent Squid proxy server with real-time HTTP virus scanning on Mandrake 10.0 using DansGuardian and ClamAV?

People quickly and easily access volumes of research on the Internet and correspond with a mouse click. For more and more companies, content filtering is part of the large battle to combat all kinds of online threats, including hackers, worms and viruses. Linux content filtering allows administrators to configure and manage Internet access across the entire network and to block unwanted Web content like pornography, shopping Web sites, games and gambling.

This guide contains all the necessary information for installing and understanding the architectural layout of the implementation. It was written with the assumption that you understand how to install programs and have a basic understanding of Linux Mandrake. This includes installing Linux Mandrake and RPM packages, editing files, making directories, compiling software and understanding general UNIX commands. This guide doesn’t explain how to use or configure Squid, DansGuardian and ClamAV but information on where to obtain this information can be found in the “Additional information” section.
Web-based applications and online marketing solutions - LumoLink