You may consider this article as somewhat of a "part two" of the Command line programs for everyday use in linux article I wrote a few days ago. It's all about going step-by-step to get you, the user, proficient at the command-line and become envy material for your friends. The distribution chosen for this is Ubuntu, but these commands that are about to be exposed will work on any other Linux system you might encounter, and you will be warned when there are exceptions. What you will get is a how-to about how to accomplish various tasks using the command-line. And one of the advantages is that you can use these commands regardless of desktop environment or lack thereof. You are only required to have a minimal Linux knowledge base for this article, so get to your terminals and let's start.
The reasons you might want to go the command-line way can be coercion (your graphics driver started driver decided to stop working all of a sudden) or, better, because you don't want to rely on the distro-specific tools Ubuntu offers. Or you don't have a GUI at all because you want to install Ubuntu server and ... GUIs and servers don't mix that well. You don't want to be in a situation when you're deprived of the graphical UI and you start panicking because you have no idea how to do anything at the command line. This article is here to help you.
In my experience, that's one of the most common scenarios when the new user starts sweating in front of a terminal: you have to start the system and realize that you have no Internet connection configured. What to do and where to start? The command you're looking for is ifconfig, and of course I recommend reading that manual page. But what you'll read here should suffice to get up and running, unless you have some exotic string-and-tin-can way of connecting to the outside world. First let's see if your network card (we will start with wired networking) is recognized by the system:
# ifconfig -aRead more ...
Virtualization packages are means for users to run various operating systems without "bare-metal" hardware - basically, you can run more than one operating system on a single computer without dual-booting or similar approaches. Virtualization software emulates a real machine and "fools" the guest operating system into thinking it's running on a real computer. Besides the more obvious advantages, virtual machines help create a greener and easier to administer computing environment. Looking at the trends in the IT industry, virtualization has seen quite a boom in the last few years, because it fits the concepts of utility computing and/or software as a service. Virtualization can be useful to you if you are an enterprise architect, developer, a home user or basically everything in between. We will begin with a short introduction about virtualization in general, then we will specifically treat VirtualBox and KVM as they seem to be most popular open source full virtualization solutions. You are expected to know your way around Linux systems, how to install a Linux distribution and how to install software on it, although we will show you how to install the two aforementioned virtualization packages on some of the popular Linux distributions.
There are two types of virtualization : one that can run the guest system as-is (as in, unmodified) and another that request a modified kernel on the guest's side in order to run. The first category is named full virtualization, because it emulates a complete hardware environment, the second is named paravirtualization , because it doesn't emulate hardware and hence needs special modifications at guest level, a good example of this type of virtualization being Xen. These are part of a bigger category named hardware virtualization, but there are also other (software, network or storage, amongst others) virtualization types, which we will not detail here. The two pieces of software we will talk about fit into the full virtualization category. Other popular hardware virtualization technologies include QEMU, Bochs, VMware, Parallels, HyperV or OpenVZ.Read more ...
Every Linux user, after a while, starts creating a toolbox that he/she takes with him/her everywhere. However, that depends on the task at hand. You might need to install a distribution, you might just need a livecd, doing security-related work or just backup. And so the toolbox gets bigger and bigger, thus becoming less and less convenient. The subject of today's article is NetbootCD. NetbootCD is not a supplement for a live Linux environment, but rather it is designed to help you install multiple Linux distributions using a single multiboot disk as oppose to requirement of 7 Linux installation disks.
In this sense NetbootCD is a CD disk that will allow you to netinstall various distributions by offering you a simple menu so you can choose distro/version and other simple options. From this reason a decent Internet connection is absolute must. You will only need the knowledge to install your distribution of choice, which nowadays is a walk in the park, with simple and easy to use installers present in many Linux distributions. We will show you how to use the NetbootCD and also how to hack it in order to add more distributions to the list, provided you have some scripting knowledge. Actually, you can use the disk also as a basic live Linux distribution, but more on that later.
NetbootCD is based on Tiny Core Linux, so you won't have to get some huge ISO. One can download disk images and put it on a CD. There is also an option to put it on floppies, but that will not be dealt with here, since floppies are error-prone and almost extinct. The above link will guide you, however, should you really want to choose the floppy way. We recommend at least 512 MB of memory, more with Fedora, because the kernel and initrd images of the distros you choose will be downloaded to RAM. Now, let's see what we get with NetbootCD.Read more ...
I must admit, I'm a command line geek. Whenever I have the chance, regardless of desktop environment or distribution, I open a terminal and start fiddling something. This does not mean everyone must be like me, of course. If you're the person who is mouse and GUI-oriented, no problems. However, there are situations when all you have at your disposal for a while is the command line. One of those situations might be an upgrade of your kernel/graphics drivers that leave you high and dry until the bug is reported and the developers look at the issue. You have to send a very important e-mail or you have to check the evolution of prices of your favorite laptop. All the essential desktop tasks (with some exceptions, though) that you do on a GUI-enabled machine can be done on a CLI-only machine as well, so if you're interested...
The everyday tasks we will refer to are the ones we usually do in a usual day, be it a work day or a weekend. We need to check our mail, maybe watch something on Youtube (yes, it's possible), chat with our friends or simply browse away from URL to URL. These are the kinds of things we are talking about in this article. By the way, another huge advantage of the CLI approach is (besides efficiency and low resources) uniformity. You don't have to worry, if you use many Linux computers, that some of them won't have your favorite desktop installed: these programs we will tell you about work everywhere, GUI available or not, as long as you have a terminal emulator installed, of course. Note that this article is comprised only of ideas and suggestions, and will not guide you step-by-step on how to use the presented applications.
On Debian, when I wanted to do 'links -g', I got "Graphics not enabled when compiling (use links2 instead for graphics mode)". After installing it, typing
$ links2 -gRead more ...
/vardirectory has filled up and you are left with with no free disk space available. This is a typical scenario which can be easily fixed by mounting your
/vardirectory on different partition. Let's get started by attaching new storage, partitioning and creating a desired file system. The exact steps may vary and are not part of this config article. Once ready obtain partition UUID of your new var partition eg. /dev/sdc1:
# blkid | grep sdc1 /dev/sdc1: UUID="1de46881-1f49-440e-89dd-6c32592491a7" TYPE="ext4" PARTUUID="652a2fee-01"Create a new mount point and mount your new partition:
# mkdir /mnt/newvar # mount /dev/sdc1 /mnt/newvarRead more ...
/lib/systemd/system/docker.servicewith your favorite text editor and replace the following line where
/new/path/dockeris a location of your new chosen docker directory:
FROM: ExecStart=/usr/bin/docker daemon -H fd:// TO: ExecStart=/usr/bin/docker daemon -g /new/path/docker -H fd://Read more ...
Whether you're a home user or a system/network administrator at a large site, monitoring your system helps you in ways you possibly do not know yet. For example, you have important work-related documents on your laptop and one fine day, the hard drive decides to die on you without even saying goodbye. Since most users don't make backups, you'll have to call your boss and tell him the latest financial reports are gone. Not nice. But if you used a regularly started (at boot or with cron) disk monitoring and reporting piece of software, like smartd for example, it will tell you when your drive(s) start to become weary. Between us, though, a hard drive may decide to go belly up without warning, so backup your data.
Our article will deal with everything related to system monitoring, whether it's network, disk or temperature. This subject usually can form enough material for a book, but we will try to give you only the most important information in order to get you started, or, depending on experience, have all the info in one place. You are expected to know your hardware and have basic sysadmin skills, but regardless where you're coming from, you'll find something useful here.
Some "install-everything" distributions may have the package needed for you to monitor the system temperature already there. On other systems, you may need to install it. On Debian or a derivative you can simply do
# aptitude install lm-sensorsRead more ...
Here is a small tip on how to determine OS of the remote computer using nmap command. This can be quite handy if you are trying to create inventory list of your LAN hosts or you simply do not know what is running behind certain local or remote IP address and you need some hints. Using nmap for this kind of job does not mean that you will be able to identify remote OS with 100% accuracy but nmap will certainly provide you with some quite solid educated guess.
When trying to determine OS of the remote host using nmap, nmap will base its guess on various aspects such as open and closed ports of default OS installation, operating system fingerprints already submitted to nmap database by other users, MAC address etc.Read more ...
What you're reading is only the first of the many articles from the "Learning Linux commands" series. Why would we want to do such a thing? Because it's useful to you to have every option and possible use of a widely used command all in one place. You will find some options or even some commands that you didn't even knew existed, and your life as a Linux user / admin will become easier. If you're not afraid of opening a terminal and know the basics of using a Linux system, this article is for you.
We chose dd as the first contender in our series because it's a useful tool that has lots of options, as you will see. This makes it almost one of the Swiss army knives of the Linux world. Yeah, this term (Swiss army knife) is used more than it should be by the Linux-oriented article writers, so we couldn't pass the opportunity to use it ourselves.
Before we start we wanted to give you a general idea of how dd is used. First of all, the name comes from "data duplicator", but it's also jokingly said to stand for "disk destroyer" or "data destroyer" because it's a very powerful tool. So we recommend extra care when using dd because one moment of carelessness may cost you valuable data. The general syntax of a dd command is
# dd if=$input_data of=$output_data [options]
Input and output data can be disks, partitions, files, devices...mainly everything you can write to or read from. As you will see, you can use dd in a networked context to send data streams across your LAN, for example. You can have only the input part in your dd command, or only the output command, and you can even eliminate both in some cases. All these will be treated in the table below.
Join command is yet another example of text processing utility under GNU/Linux. Join command combines two files based on the matching content lines found in each file. Using join command is quite straight forward and if used currently and in the right situation it can save lots of time and effort. This article requires very basic command line experience.