Sandra Henry-Stocker

Author Archives: Sandra Henry-Stocker

How to list repositories on Linux

A Linux repository is a storage location from which your system retrieves and installs OS updates and applications. Each repository is a collection of software hosted on a remote server and intended to be used for installing and updating software packages on Linux systems. When you run commands such as “sudo apt update” or “sudo apt upgrade”, you may be pulling package information and package updates from a number of repositories.Repositories contain thousands of programs. Standard repositories provide a high degree of security, since the software included is thoroughly tested and built to be compatible with a particular distribution and version. So, you can expect the updates to occur with no unexpected "side effects."To read this article in full, please click here

Linux tricks that can save you time and trouble

Good Linux command line tricks don’t only save you time and trouble. They also help you remember and reuse complex commands, making it easier for you to focus on what you need to do, not how you should go about doing it. In this post, we’ll look at some handy command line tricks that you might come to appreciate.Editing your commands When making changes to a command that you're about to run on the command line, you can move your cursor to the beginning or the end of the command line to facilitate your changes using the ^a (control key plus “a”) and ^e (control key plus “e”) sequences.You can also fix and rerun a previously entered command with an easy text substitution by putting your before and after strings between ^ characters -- as in ^before^after^.To read this article in full, please click here

Linux tricks that even you can love

Good Linux command line tricks don’t only save you time and trouble. They also help you remember and reuse complex commands, making it easier for you to focus on what you need to do, not how you should go about doing it. In this post, we’ll look at some handy command line tricks that you might come to appreciate.Editing your commands When making changes to a command that you're about to run on the command line, you can move your cursor to the beginning or the end of the command line to facilitate your changes using the ^a (control key plus “a”) and ^e (control key plus “e”) sequences.You can also fix and rerun a previously entered command with an easy text substitution by putting your before and after strings between ^ characters -- as in ^before^after^.To read this article in full, please click here

How to pin a pile of addresses onto a Google map

Turning a list of names, addresses and related information into a Google map is a lot easier than you might think. The effort required depends, as you might imagine, on the information that you starting with. But if the format is fairly consistent, it’s relatively easy to massage the information into a form that can be uploaded into a format that works.First, what you can expect Once you’ve loaded a list of names and addresses into a Google map, you will be able view the location of each person and set up your map such that clicking on any of the map markers displays the information collected for that address.To read this article in full, please click here

Linux kernel 4.18: Better security, leaner code

The recent release of Linux kernel 4.18 followed closely by the releases of 4.18.1, 4.18.2, 4.18.3, 4.18.4, and 4.18.5 brings some important changes to the Linux landscape along with a boatload of tweaks, fixes, and improvements.While many of the more significant changes might knock the socks off developers who have been aiming at these advancements for quite some time, the bulk of them are likely to go unnoticed by the broad expanse of Linux users. Here we take a look at some of the things this new kernel brings to our systems that might just make your something-to-get-a-little-excited-about list.[ Also read: Invaluable tips and tricks for troubleshooting Linux ] Code Cleanup For one thing, the 4.18 kernel has brought about the surprising removal of nearly 100,000 lines of outdated code. That's a lot of code! Does this mean that any of your favorite features may have been ripped out? That is not very likely. This code cleanup does means that a lot of code deadwood has been carefully expunged from the kernel along with one significant chunk. As a result, the new kernel should take up less memory, Continue reading

Is the Linux 4.18 kernel heading your way?

How soon the 4.18 kernel lands on your system or network depends a lot on which Linux distributions you use. It may be heading your way or you may already be using it.If you have ever wondered whether the same kernel is used in all Linux distributions, the answer is that all Linux distributions use the same kernel more or less but there are several big considerations that make that "more or less" quite significant. Most distributions add or remove code to make the kernel work best for them. Some of these changes might eventually work their way back to the top of the code heap where they will be merged into the mainstream, but they'll make the distribution's kernel unique -- at least for a while. Some releases intentionally hold back and don't use the very latest version of the kernel in order to ensure a more predictable and stable environment. This is particularly true of versions that are targeted for commercial distribution. For example, RHEL (Red Hat Enterprise Edition) will not be nearly as aggressively updated as Fedora. Some distributions use a fork called Linux-libre, which is Linux without any proprietary drivers built in. It omits software Continue reading

How the L1 Terminal Fault vulnerability affects Linux systems

Announced just yesterday in security advisories from Intel, Microsoft and Red Hat, a newly discovered vulnerability affecting Intel processors (and, thus, Linux) called L1TF or “L1 Terminal Fault” is grabbing the attention of Linux users and admins. Exactly what is this vulnerability and who should be worrying about it?L1TF, L1 Terminal Fault, and Foreshadow The processor vulnerability goes by L1TF, L1 Terminal Fault, and Foreshadow. Researchers who discovered the problem back in January and reported it to Intel called it "Foreshadow". It is similar to vulnerabilities discovered in the past (such as Spectre).This vulnerability is Intel-specific. Other processors are not affected. And like some other vulnerabilities, it exists because of design choices that were implemented to optimize kernel processing speed but exposed data in ways that allowed access by other processes.To read this article in full, please click here

How the L1 Terminal Fault vulnerability affects Linux systems

Announced just yesterday in security advisories from Intel, Microsoft and Red Hat, a newly discovered vulnerability affecting Intel processors (and, thus, Linux) called L1TF or “L1 Terminal Fault” is grabbing the attention of Linux users and admins. Exactly what is this vulnerability and who should be worrying about it?L1TF, L1 Terminal Fault, and Foreshadow The processor vulnerability goes by any of those names. Researchers who discovered the problem back in January and reported it to Intel called it "Foreshadow". It is similar to vulnerabilities discovered in the past (such as Spectre).This vulnerability is Intel-specific. Other processors are not affected. And like some other vulnerabilities, it exists because of design choices that were implemented to optimize kernel processing speed but exposed data in ways that allowed access by other processes.To read this article in full, please click here

Examining partitions on Linux systems

Linux systems provide many ways to look at disk partitions. In this post, we'll look at a series of commands, each which shows useful information but in a different format and with a different focus. Maybe one will make your favorites list.lsblk One of the most useful commands is the lsblk (list block devices) command that provides a very nicely formatted display of block devices and disk partitions. In the example below, we can see that the system has two disks (sda and sdb) and that sdb has both a very small (500M) partition and a large one (465.3G). Disks and partitions (part) are clearly labeled, and the relationship between the disks and partitions is quite obvious. We also see that the system has a cdrom (sr0).To read this article in full, please click here

How to display data in a human-friendly way on Linux

Not everyone thinks in binary or wants to mentally insert commas into large numbers to come to grips with the sizes of their files. So, it's not surprising that Linux commands have evolved over several decades to incorporate more human-friendly ways of displaying information to its users. In today’s post, we look at some of the options provided by various commands that make digesting data just a little easier.Why not default to friendly? If you’re wondering why human-friendliness isn’t the default –- we humans are, after all, the default users of computers — you might be asking yourself, “Why do we have to go out of our way to get command responses that will make sense to everyone?” The answer is primarily that changing the default output of commands would likely interfere with numerous other processes that were built to expect the default responses. Other tools, as well as scripts, that have been developed over the decades might break in some very ugly ways if they were suddenly fed output in a very different format than what they were built to expect.To read this article in full, please click here

Displaying data in a human-friendly way on Linux

Not everyone thinks in binary or wants to mentally insert commas into large numbers to come to grips with the sizes of their files. So it's not surprising that Linux commands have evolved over several decades to incorporate more human-friendly ways of displaying information to its users. In today’s post, we’re going to look at some of the options provided by various commands that make digesting data just a little easier.Why not default to friendly? If you’re wondering why human-friendliness isn’t the default –- we humans are, after all, the default users of computers -- you might be asking yourself “Why do we have to go out of our way to get command responses that will make sense to everyone?” The answer is primarily that changing the default output of commands would likely interfere with numerous other processes that were built to expect the default responses. Other tools as well as scripts that have been developed over the decades might break in some very ugly ways if they were suddenly fed output in a very different format than what they were built to expect. It’s probably also true that some of us might prefer to see all of Continue reading

How to query your Linux system kernel

How much can your Linux system tell you about the kernel it's running and what commands are available to help you ask? Let's run through some of them.uname The simplest and most straight-forward command for providing information on your kernel is the uname -r command. It provides a succinct answer to your question but in a format that also includes a number of fields each which provides a particular piece of information.$ uname -r 4.15.0-30-generic ^ ^ ^ ^ ^ | | | | | | | | | | | | | | +-- the distribution-specific string | | | +------- the latest bug fix | | +---------- the minor revision | +------------ the major revision +--------------- the kernel version Add an "s" and your output will include the kernel's name:To read this article in full, please click here

How to use the gpg command to encrypt Linux files

There are many reasons to encrypt files — even on a system that is well maintained and comparatively secure. The files may highly sensitive, contain personal information that you don't want to share with anyone, or be backed up to some variety of online storage where you'd prefer it be extra secure.Fortunately, commands for reliably encrypting files on Linux systems are easy to come by and quite versatile. One of the most popular is gpg.gpg vs pgp and OpenPGP Used both to encrypt files in place and prepare them to be sent securely over the Internet, gpg is related to, but not the same as, pgp and OpenPGP. While gpg is based on the OpenPGP standards established by the IETF, it is — unlike pgp — open source. Here's the rundown:To read this article in full, please click here

Is it time to start climbing the ladder to Kubernetes?

Kubernetes is one of the most important innovations to hit Linux in decades — and one that's making big changes in how critical services are being deployed. It’s not an operating system, an app, or a container, but a container-specific management environment — and it's making applications and services remarkably more manageable.You can think of Kubernetes as a portable cloud platform, as a container platform, or as a microservices platform that takes advantage of both the simplicity of Platform as a Service (PaaS) and the flexibility of Infrastructure as a Service (IaaS). Regardless of how you define it, what you get by investing your time and technology in Kubernetes will be some very impressive options for:To read this article in full, please click here

Examining Linux system performance with dstat

Want to do a quick performance check on your Linux system? You might want to take a look at the dstat command. Dstat provides valuable insights into Linux system performance, pretty much replacing a collection of older tools such as vmstat, netstat, iostat, and ifstat with a flexible and powerful command that combines their features.With this one command, you can look at virtual memory, network connections and interfaces, CPU activity, input/output devices and more. In today's post, we'll examine some dstat commands and see what they can show you about your systems. [ Two-Minute Linux Tips: Learn how to master a host of Linux commands in these 2-minute video tutorials ] Dstat options and defaults First, let's start with a fairly simple command. With the dstat -c (CPU) option, dstat displays CPU stats. In the example below, we're asking for two-second intervals and six reports.To read this article in full, please click here

Converting and manipulating image files on the Linux command line

Most of us probably know how wonderful a tool Gimp is for editing images, but have you ever thought about manipulating image files on the command line? If not, let me introduce you to the convert command. It easily coverts files from one image format to another and allows you to perform many other image manipulation tasks as well -- and in a lot less time than it would take to make these changes uses desktop tools. Let's look at some simple examples of how you can make it work for you.Converting files by image type Coverting an image from one format to another is extremely easy with the convert command. Just use a convert command like the one in this example:To read this article in full, please click here

The aftermath of the Gentoo GitHub hack

Gentoo GitHub hack: What happened? Late last month (June 28), the Gentoo GitHub repository was attacked after someone gained control of an admin account. All access to the repositories was soon removed from Gentoo developers. Repository and page content were altered. But within 10 minutes of the attacker gaining access, someone noticed something was going on, 7 minutes later a report was sent, and within 70 minutes the attack was over. Legitimate Gentoo developers were shut out for 5 days while the dust settled and repairs and analysis were completed.The attackers also attempted to add "rm -rf" commands to some repositories to cause user data to be recursively removed. As it turns out, this code was unlikely to be run because of technical precautions that were in place, but this wouldn't have been obvious to the attacker.To read this article in full, please click here

The aftermath of the Gentoo GitHub hack

Gentoo GitHub hack: What happened? Late last month (June 28), the Gentoo GitHub repository was attacked after someone gained control of an admin account. All access to the repositories was soon removed from Gentoo developers. Repository and page content were altered. But within 10 minutes of the attacker gaining access, someone noticed something was going on, 7 minutes later a report was sent, and within 70 minutes the attack was over. Legitimate Gentoo developers were shut out for 5 days while the dust settled and repairs and analysis were completed.The attackers also attempted to add "rm -rf" commands to some repositories to cause user data to be recursively removed. As it turns out, this code was unlikely to be run because of technical precautions that were in place, but this wouldn't have been obvious to the attacker.To read this article in full, please click here

Is implementing and managing Linux applications becoming a snap?

Quick to install, safe to run, easy to update, and dramatically easier to maintain and support, snaps represent a big step forward in Linux software development and distribution. Starting with Ubuntu and now available for Arch Linux, Debian, Fedora, Gentoo Linux and openSUSE, snaps offer a number of significant advantages over traditional application packaging. Compared to traditional packages, snaps are: easier for developers to build faster to install automatically updated autonomous isolated from other apps more secure non-disruptive (they don't interfere with other applications) So what are snaps? Snaps were originally designed and built by Canonical for use on Ubuntu. The service might be referred to as “snappy”, the technology “snapcraft”, the daemon “snapd” and the packages “snaps”, but they all refer to a new way that Linux apps are prepared and installed. Does the name “snap” imply some simplification of the development and installation process? You bet it does!To read this article in full, please click here

Shredding files on Linux

The rm command easily makes files disappear from our file listings, but what does it actually do and how can we ensure that files are unlikely to be recoverable?A little background To understand what happens when you remove a file from a Linux system with rm, first think about inodes -- those intriguing data structures that keep track of all of a file's attributes -- often called "metadata" -- that describe the file. This includes its name, its owner and group, what permissions have been established and where the file's contents can be found on the disk.Next, think about Linux directories. While they take the appearance and character of folders (i.e., merely containers for holding files) they are actually files themselves -- files that include no more than the names and inode numbers of the files they "contain". So, what we get is a convenient way to think about directories and files in the same way you might think about the folders and paperwork in your file cabinets (if any of you still have one of those).To read this article in full, please click here

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