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Member since: June 2008
Sandra Henry-Stocker has been administering Unix systems for more than 25 years. She describes herself as "USL" (Unix as a second language) but remembers enough English to write books and buy groceries. She currently works for TeleCommunication Systems -- a company that builds innovative technologies to make critical connections happen -- where no one else necessarily shares any of her opinions. Send comments and suggestions to firstname.lastname@example.org.
- Iptables, more properly referred to as "iptables/netfilter" because of the two modules that are involved -- the userspace module "iptables" and the kernel module "netfilter" -- is the firewall that you'll find running by default on most Linux systems today.
25 weeks 5 days ago
- Setting limits on your Linux systems can both protect against certain types of failure and ensure that critical processes keep running when systems are heavily used. Take a look at the ulimit command and see what kind of shackles are limiting you – or maybe setting you free.
26 weeks 5 days ago
- The most typical use of Samba is to make Unix home directories or shared files available on Windows. Being most comfortable on the command line, I generally do this by opening a Command Prompt and entering NET USE commands.
27 weeks 4 days ago
- With the clocks turned back and the Big Vote about to happen, I'm up for a bit of nostalgia. And nothing pleases me more than doting on some of my favorite Unix commands, aliases and "tricks".
28 weeks 4 days ago
- I call this blog "Unix as a Second Language" for a reason. I spoke English long before I became a Unix geek and a well crafted sentence can still bring a thrill to my geeky little heart. The problem is that I find myself increasingly surrounded by people who just don't get some of the basic principles of the language.
29 weeks 4 days ago
- LVM (currently released as LVM2), the "logical volume manager", is a flexible storage manager for the Linux kernel. It allows you to add, remove and resize partitions to suit your needs.
30 weeks 4 days ago
- Just about anyone who works on the command line of a Unix/Linux systems knows about history. Having the ability to repeat their most recent command by just typing !! or the most recent command that starts with a particular letter by typing something like !s saves them a lot of typing and a lot of typos.
31 weeks 4 days ago
- If you've been thinking that you could really use an Intranet site for your small business, but you're worried about the costs associated with building and maintaining one yourself, you might want to take a look at Bitrix24.
32 weeks 5 days ago
- In the olden days of Unix, each file had an owner, a group, and a notion of "everybody else". These entities could be granted read, write and/or execute permission -- and that was as far as it went.
33 weeks 4 days ago
- More than a few Linux distributions have pulled up their stakes in the decades old System V method of booting and quietly moved to a better way of booting. Better, faster, easier to maintain, and less prone to problems.
34 weeks 5 days ago
- Anyone too comfortable with the idea of run states on Unix systems might not be ready to hear this, but the process of going from a cold piece of hardware to multi-user mode has taken a couple very sharp turns in the last six years or so.
35 weeks 5 days ago
- Linux has gone a long way to popularize the use of sudo.
36 weeks 4 days ago
- Q: Why don´t you see penguins in Britain? A: Because they´re afraid of Wales But, if you did, they'd probably be reading this fun new book -- Ubuntu Made Easy: A Project-Based Introduction to Linux, no starch press, 2012 is the most easy-to-read, properly pitched and fun Linux book that I've ever read.
37 weeks 5 days ago
- Over the years, the primary way that I've used sed is to change text on the fly. There are many occassions in which I want to change one string to another the first or every time that it appears in a file or command output. $ sed 's/2011/2012/' new $ sed s/tomorrow/today/ msg2 $ sed 's/,/:/g' < file
38 weeks 5 days ago
- Most admins monitoring system performace with sar (sysstat) collect performance data over the span of a week or two, but you can easily extend this to four weeks. In fact, you can extend the coverage period to well beyond a month if you need to maintain a longer view of performance and if you have enough disk space to hold all the data.
39 weeks 5 days ago
- Some Unix/Linux systems require that a username and password be entered for login. Some can be set up to log you in automatically. For Lubuntu -- a lightweight version of the popular Ubuntu distribution, you can move between these two login options with a mere flick of your wrist and a wee bit of editing.
40 weeks 5 days ago
- The best way to learn Linux is to use it. A good introductory book will help, but you won't really learn Linux or become confident in your skills unless you park yourself in front of a Linux system and start typing (and popping windows open, creating files, find your way around the desktop ...).
41 weeks 6 days ago
- sar on Linux If the sysstat package isn't installed on your Linux system (which it generally isn't by default), you can easily grab a copy with your favorite Linux installer -- typically one of the following commands will do the job: yum install sysstat apt-get install sysstat
42 weeks 5 days ago
- Monitoring system performance with sar is as easy as enabling the sar tasks. While sar is bundled into many versions of Unix, it's often disabled until you take steps to get it running. To find out whether sar is running on your Unix server, just type sar and see what happens.
43 weeks 5 days ago
- A key element in the ISO 27001 certification process is to identify and assess risks. While this idea may seem obvious, you may be surprised at how much you can learn about your systems, processes and security threats by pushing them through this very systematic process.
44 weeks 5 days ago
- The first step toward ISO 27001 (even before blowing your budget on the PDFs) is to establish and heartily commit to the reasons you're pursuing certification.
45 weeks 5 days ago
- Back in 2005, a new series of ISO standards made an appearance on the international stage of certifications (try to suppress the image of large wads of paper assembled in a Broadway kick line).
46 weeks 4 days ago
- Poor man's load balancing is properly called Round Robin DNS. Using this technique, you set up a series of A records in DNS, each with the same name, but pointing to a different IP address. As an example, say we want to balance web traffic amount five separate servers. We could set up five A records like this:
47 weeks 5 days ago
- When your Linux server starts feeling sluggish, you might benefit from looking at your swap space and gauging whether it's adequately sized for your system's workload. Fortunately, Linux has some handy commands for helping you get a good picture of your system's behavior.
48 weeks 5 days ago
- Let's look at some basic commands that report on memory usage. The first that probably comes to mind is free. The free command will tell you about used and unused memory and about swap space. Physical memory is the random access storage provided by the RAM modules plugged into your motherboard.
49 weeks 6 days ago
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