LINUX NEWS
RESOURCES & LINKS FROM BRAINBUZZ.COM
Thursday, June 7, 2001
Read By 6,000 Linux Enthusiasts Weekly!TABLE OF CONTENTS
1) Sean’s Notes
2) Linux News
RedHat Unveils 7.1 for the Itanium
Where Did All the IPs Go?
New Cluster Options
VA Linux. Ouch.3) Linux Resources
Linux Network Administrator's Guide
CGI Security
Getting Started on Email Services with Linux
AMANDA Network Backup Made Easy
Opening Sockets in PHP4) App o’ the week
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1) Sean’s Notes
A couple of weeks ago, I was demonstrating the cron system:
http://www.ertw.com/~sean/newsletter/May+17%2C+2001 http://www.ertw.com/~sean/newsletter/May+24%2C+2001
Cron allows you to submit jobs to be run at regularly scheduled times, such as log processing, or other system maintenance. There is another, similar, system called “at” that lets you schedule one-off jobs quite easily.
For example, I’d like to remind myself to leave early this Friday:
$ at 4pm friday at> xmessage -display bob:0.0 Go home at> <EOT> job 5 at 2001-06-08 16:00
Start off by typing “at”, followed by the description of the time. It is quite flexible, in this case “4pm friday” is interpreted to mean this upcoming friday at 1600. You will then be prompted with “at>” for the commands you want to execute. In this case, I’m going to pop up a window with the xmessage command. Since this is going to be running with a stripped environment, I need to specify the X display that the message will pop up on. Then I pass the message, “Go home”. At the next at> prompt, I enter Control-D which means that I’m done. The response to that is a confirmation that the job has been scheduled for the correct date. Come Friday, I’ll be out early enough that I don’t get caught in traffic!
If I were so inclined, I could verify the job was still there:
$ atq 5 2001-06-08 16:00 a sean
Yep…Job 5 is scheduled to run on Friday at 4pm. But now I get a call from my mean old boss, saying that I have to work late on Friday! The nerve! Guess I’d better delete that job.
$ atrm 5 $ atq $
Well, I’ll be sure to get an early start for next week:
$ at 4pm next friday at> …
Some other helpful uses of the command follow.
Run the contents of the /usr/local/bin/report (rather than typing in the whole thing) at 1 pm, tomorrow:
$ at 1pm tomorrow -f /usr/local/bin/report
or, two days from now, at midnight:
$ at midnight + 2 days
Specify the date to avoid confusion:
$ at 4pm Jun 9
If you leave out the time, it will run at the current time, on the date you specify
$ date +%H:%M 20:28 $ at Jun 9 … job 15 at 2001-06-09 20:28
And, my favourite,
$ at teatime
(Teatime is 4pm, for those that didn’t know)
So as you can see, UNIX offers some very powerful scheduling capabilities. You can schedule jobs to run regularly with cron, or do one-off jobs with at. There is even another one, batch, that will run jobs when the system load gets below a certain amount.
Long live the Penguin,
Sean mailto:swalberg@brainbuzz.com
Visit the Linux News Board at http://boards.brainbuzz.com/boards/vbt.asp?b2
2) Linux News
RedHat Unveils 7.1 for the Itanium
The nice thing about having an OS that you have the source to, and that of the compilers, is that you can build a version that specifically takes advantage of higher end processors. RedHat has just released a version of 7.1 targeted towards Intel’s Itanium processor.
http://www.redhat.com/products/software/linux/7-1_itanium.html
Where Did All the IPs Go?
This is an interesting news piece on why free software should hop on the IPv6 bandwagon. It also gives some views on why we are where we are now, when the whole thing might have been preventable.
http://www.onlamp.com/pub/a/onlamp/2001/03/02/ip_gone.html
New Cluster Options
A startup, Lineo, has taken the wraps off a nice Linux cluster solution. This one uses a SAN (Storage Area Network) to facilitate the inter-node communication. Prices look reasonable for some of the more medium sized players.
http://www.zdnet.com/enterprise/stories/linux/0,12249,2764358,00.ht ml
VA Linux. Ouch.
VA Linux recently reported a 41% drop in sales. “Ouch” is all I can say. A huge restructuring charge didn’t help, but at least the company is optimistic.
http://www.theregister.co.uk/content/4/19134.html
3) Linux Resources
Linux Network Administrator’s Guide
This guide started off in the Linux Documentation Project, then O’Reilly cleaned it up a bit and made a printed version. Seems they’ve done some revisions, and released it to the world over the Web. This is a handy reference guide!
http://www.oreilly.com/catalog/linag2/book/index.html
CGI Security
CGIs are notorious for being insecure. This is mostly because web developers are not security experts, and vice-versa. CGISecurity.com is devoted to bringing forward serious issues in CGIs out there, and to promote secure CGI coding practices.
http://www.cgisecurity.com/
Getting Started on Email Services with Linux
Email is a great thing, but is very complex in the back end. It’s also a great project to set out on if you want to learn about UNIX, because it will force you to use a lot of the OS’ features to get it going. This is one man’s documentation at his attempts to get email set up.
http://www.linux.com/learn/newsitem.phtml?sid=1&aid386
AMANDA Network Backup Made Easy
Anyone who has ever asked me what to use for backing up will have heard me rant about AMANDA. They usually come back the next day asking how anyone is supposed to configure it. This document gives the rundown on this task, which can be a bit daunting to even the experienced Linux hacker.
http://linuxnewbie.org/nhf/intel/software/amandanetwork.html
Opening Sockets in PHP
PHP is a great server-side web scripting package. It can do pretty much anything. As this article shows, PHP can perform socket calls, which the author uses to speak NNTP and fetch USENET articles.
http://www.phpbuilder.com/columns/armel20010427.php3
4) App o’ the week
If you’re working with LDAP, this is a great tool to have. It presents you with a graphical view of your tree, and allows for editing and reorganization. It’s easy enough that non technical people can use it!
http://www-unix.mcs.anl.gov/~gawor/ldap/
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