Letters to the Editor
Hi! I would like to thank you for doing so interesting a journal. It's my second subscription to LJ, and it won't be the last. I found the XForms review and tutorial so interesting that I decided to test it and will, perhaps, even use it at work. I enjoy reading tutorials and explanations about the Linux kernel (thanks a lot to Michael K. Johnson and all the staff of Linux Journal).
You try to spread the Linux enthusiasm everywhere. It's a success. Thank you.
Juergen Schmidt, an attentive reader, reported a few errors in the third Kernel Korner article about device drivers, co-authored by Georg van Zezchwitz and myself. The errors are my fault, due to the limited time I had to revise the article.
The code printed within the article comes from a real driver, and it is known to run, but sometimes, I forgot to substitute the name of a symbol while copying from the real driver to the article's text.
So, Skel_Board (the structure) should read as Skel_Hw; hwp (the pointer) is equivalent to board (replace either one with the other); in skel_select, file (the struct file pointer) should read filp.
I'm sorry for these inconsistencies, and I hope they didn't cause headaches to the readers.
—Alessandro Rubini email@example.com
I have a few corrections to my article Building a Linux Firewall in LJ #24, April 1996, page 49.
1) Figure 3 is a duplicate of Figure 2. This is my fault. I submitted it this way. Obviously, cut-and-paste from one xterm to another can either be your friend or your enemy. I must have copied from the wrong window. The correct contents for the figure are shown here:
# ipfw -n list b Type Proto From To Ports deny udp anywhere 192.168.1.1/32 any -> any deny udp anywhere 18.104.22.168/32 any -> any accept udp anywhere 22.214.171.124/32 domain -> any accept udp 126.96.36.199/24 188.8.131.52/32 any -> snmp deny tcp anywhere 184.108.40.206/32 any -> any deny tcp anywhere 192.168.1.1/32 any -> any
Figure 3. New blocking rule for SNMP to only accept from 220.127.116.11.
I've squeezed that down. Please use a condensed courier font to make it fit, or somehow make it a wide inline figure.
2) Several of the ipfwadm commands on page 58 have an additional character within the command line. The character is a right angle bracket, and this could cause some undesirable side effects if typed in that way.
3) The sentence on page 53 “ipfw only supports the deny and accept policies, not reject.” should be corrected to, “ipfw only supports the deny and accept policies for its output. A rule set to reject will still show up as deny.”
—Chris Kostick firstname.lastname@example.org
During the Space Shuttle mission STS-75, an astronaut was heard talking about the fact that Linux was installed on a computer on board the spacecraft. A few weeks later, the computer's function was disclosed. The software in use was X-based software developed under Digital Unix and ported to Linux so that it could be used on board the shuttle. Astronaut Ron Parise said in an e-mail message to fellow amateur radio operators:
Pat, et al.:
Linux was installed on one of the IBM Thinkpads that are usually flown on the shuttle. This was in support of the tether experiments. Since the ground-based applications to control those experiments ran on a DEC Alpha it was easy to just port them to a Linux system for on-board use.
73's, Ron WA4SIR
Practical Task Scheduling Deployment
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.View Now!
|The Firebird Project's Firebird Relational Database||Jul 29, 2016|
|Stunnel Security for Oracle||Jul 28, 2016|
|SUSE LLC's SUSE Manager||Jul 21, 2016|
|My +1 Sword of Productivity||Jul 20, 2016|
|Non-Linux FOSS: Caffeine!||Jul 19, 2016|
|Murat Yener and Onur Dundar's Expert Android Studio (Wrox)||Jul 18, 2016|
- The Firebird Project's Firebird Relational Database
- Stunnel Security for Oracle
- My +1 Sword of Productivity
- SUSE LLC's SUSE Manager
- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- Parsing an RSS News Feed with a Bash Script
- Google's SwiftShader Released
- Doing for User Space What We Did for Kernel Space
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide