LINUX NEWS
http://www.Cramsession.com
September 5, 2002 - Issue 97TABLE OF CONTENTS
1) Sean’s Notes
2) Linux News
Verisign in Hot Water
Doc Searls Reviews Gnomedex
Dell To Build Cluster
HP Sets EOL Date for PA-RISC, Alpha3) Linux Resources
Dual Booting XP and Linux
Mozilla Laziness
Load Balancing With LVS
Automate Installs With Kickstart
The SCSI System in Action4) App o’ the Week
~~~~~~~~~~~~~~~~~~~~~~ ADVERTISEMENT ~~~~~~~~~~~~~~~~~~~~~~~
Free Quizzer for all Cramsession subscribers. Your choice of Win2K Professional, A+, Network+, CCNA, CCNP, or MetaFrame. Hundreds of Free multiple-choice questions/answers and detailed explanations, and lots of free reference material in our adaptive simulation test engine. Limit one per Cramsession subscriber. Download your FREE Quizzer at:
http://ad.brainbuzz.com/?RC06&AIV13
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For information on how to advertise in this newsletter please contact mailto:adsales@CramSession.com or visit http://cramsession.com/marketing/default.asp
1) Sean’s Notes
Now where did I put that file?
That’s a question I’ve asked myself many times. There’s another version of that question, namely:
Now where did he put that file?
The latter question is often asked when the file name is “fix_database”, the database is down, and the person referred to as “he” is unavailable (or asking himself the first question). The Unix filesystem is big, and with hard drive sizes ever increasing, odds are you’re going to misplace a file every so often. Fear not! There are some utilities out there that can help you find that lost file and save the day.
The first command is “which”. The purpose of this command is to tell you the full path to the command you type. Thus:
# which sendmail /usr/sbin/sendmail
lets me know that if I type “sendmail”, then “/usr/bin/sendmail” will be executed. If it turns out to be an alias, it’ll let you know that too:
# which ls alias ls=’ls –color=tty’ /bin/ls
The problem with “which” is that it only searches $PATH. If /usr/sbin wasn’t in my path, it would have said:
# which sendmail /usr/bin/which: no sendmail in (/spool/adabas/bin:/spool/adabas/pgm:/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:/usr/bin/X11:/usr/X11R6/bin:/root/bin)
So, a helpful command, but not always the answer.
The next one is “locate”. Every night, your system should run a command called “updatedb” which traverses your filesystem and stores the location of every file. When you type “locate foo”, it searches through this database for “foo”. Note, it’s a partial match, so it’ll match:
food /usr/food/blah aaafooaaa
More caveats – the index is only updated nightly. If, for some reason, the index doesn’t run, your database won’t be updated (if it goes for longer than a week, you’ll get a warning when you run locate). If the file was created after updatedb was run, you won’t find it either.
Later versions of the locate package actually use “slocate”, which is a secure version. It used to be that anyone could look at the whole database, so you could see the contents of people’s directories even if permissions denied it (since updatedb usually ran as root). slocate keeps track of permissions, so you only see files you normally could.
# locate fix_database /usr/scripts/fix_database.pl
Well, that’s where he stored it.
If locate doesn’t turn it up, or you want to be really flexible, “find” is what you want. Find traverses the filesystem every time you run it, so there is a penalty associated with running it. The general form of the command is:
find starting_points options
So…
find / -name fix_database.pl
…will start at the root directory, and find a file with the name “fix_database.pl” (note it’s not partial match). Since you think it’ll probably be in /usr or /home, you can give that hint:
find /usr /home -name fix_database.pl
But maybe it wasn’t “fix_database.pl”. It started with fix, and was a perl script…
find /usr /home -name fix*.pl
Note that I used * instead of . That was because I’d be typing it at the shell prompt, and I wanted to pass ”” to find, and not have the shell try to expand the wildcard before passing to find. The use of the backslash is called “escaping”, or “protecting from the shell”.
Find is also a very versatile command. You can return files owned by a certain person, or that were accessed or modified between certain periods of time, or that have a certain size range. It’s commonly used in cron to clean up temporary directories. For example, if you wanted to find all the “core” files in /home that were a month old:
find /home -name core -atime +30
or, even have it delete them:
find /home -name core -atime +30 -exec rm {} \;
(note the ; must also be protected from the shell)
So, between “find”, “which”, and “locate”, you should be able to find the file you’re looking for!
Long live the Penguin,
Sean mailto:swalberg@cramsession.com
2) Linux News
Verisign in Hot Water
Everyone’s favourite domain registrar coughnotcough is in trouble because their customer information is not up to date. People like “Toto”, living on “Yellow Brick Road” are able to register domains, and ICANN doesn’t like it.
http://news.com.com/2100-1023-956433.html?tag_top
Doc Searls Reviews Gnomedex
Gnomedex was just the other week, and the senior editor of Linux Journal gave his review of the event.
http://www.linuxjournal.com/article.php?sidc10
Dell To Build Cluster
Dell is getting into the cluster market, building a 2,000 node cluster to help the University at Buffalo with their scientific research. At 5.6 terraflops, it’ll end up on the top 500 most powerful computers in the wold.
http://news.com.com/2100-1001-956153.html
HP Sets EOL Date for PA-RISC, Alpha
Now that HP owns both the PA-RISC and Alpha lines of processors, they’ve set the End of Life dates to be the same. No news on what will happen after that, though.
http://www.theinquirer.net/?articleR56
3) Linux Resources
Dual Booting XP and Linux
Getting your regular Windows OS and Linux to coexist on one machine can be a chore. If you really want this kind of punishment, here’s the page for you.
http://www.redhat.com/advice/tips/
Mozilla Laziness
My brother showed me this trick with Mozilla that you can use to create shortcuts to almost anything. For example, if I wanted to do a google search for “linux”, I could type “gg linux” in the URL bar. Here’s a page showing how this time-saving feature can be implemented.
http://surfmind.com/lab/moz/
Load Balancing With LVS
The Linux Virtual Server project is often used to front end a web server farm so that the load gets spread out over the cluster, and so a downed machine doesn’t cause service to be affected. This article shows another use, namely load balancing X-Windows sessions across a farm of HP-UX machines.
http://www.samag.com/documents/su53/sam0209a/0209a.htm
Automate Installs With Kickstart
Features like this are why I love Red Hat. Kickstart lets you script an install of Red Hat, such that you can boot from a single floppy or CD and install a box (hands free) over the network. An old friend, njcajun, has put together a great article on getting this software up and running.
http://www.linuxlaboratory.org/modules.php?op=modload&name=Sections &file=index&req=viewarticle&artid=4
The SCSI System in Action
SCSI, as it pertains to the kernel, is implemented as a series of smaller parts, each of which serves a distinct function. This article unravels the whole thing; it’s very informative, especially if you’ve wrestled with SCSI before.
http://www.linuxplanet.com/linuxplanet/reports/4416/1/
4) App o’ the Week
- 1x is an authentication protocol used on both wireless and wired networks. Its purpose is to only allow authorized people on the network, and Cisco even uses it to assign predefined VLANs to users. This is a Linux implementation of the client.
http://www.wohnheim.uni-mainz.de/~rw/802.1x/
(C) 2002 BrainBuzz.com, Inc. All Rights Reserved.
This message is from CramSessionYou are currently subscribed to the following list Hottest Linux News and Resources as: sean@ertw.com
To un-subscribe from this newsletter by e-mail, send a blank email message to: mailto:leave-linuxnews-3825955Y@list.cramsession.com
To subscribe to this newsletter and many others visit our site at: http://newsletters.cramsession.com/signup/default.asp