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ioctl

These are the methods that device drivers provide for functions that can't be accomplished through normal i/o. For example, a tape driver will have an ioctl call to set compression. See http://aplawrence.com/Unix/lpstatus.html for more examples.



Title Last Comment
Is sed dead?  
- If you learn how to use sed, you get a bonus: the same editing commands can be used in ed and vi. -

The lowly ls command   2011/04/20 TonyLawrence
- ls might have more flags than any other Unix command and operating system variance is wide. The lowly ls command has a lot of flags, perhaps more than any other Unix command. -

quoted-printable: Tech Words the Day  
- spammers use this and other encodings to disguise their work -

Tarantella: Tech Words the Day  
- The company formerly known as SCO. Or what was left over after Caldera bought all the Unix related stuff. Tarantella makes a product that competes with Windows Terminal Server. -

dns: Tech Words the Day  
- Domain Name Service: how names like www.xyz.com are translated to ip addresses so that your packets and theirs can find one another. For many of us, DNS is simple. If we are using DHCP, we may get everything we need for DNS from the dhcp server. -

Gambas: Tech Words the Day  
- This has been described as 'Visual Basic for Linux'. However, as explained at http://gambas.sourceforge.net/, it is like Visual Basic, but is definitely not mean to be a clone. -

ClusterKnoppix: Tech Words the Day  
- More clustering. Download the cd images, follow the tutorial directions, and bingo, you have a cluster. I have a couple of semi-dead machines here that I can try this on - looks like fun! -

arts: Tech Words the Day  
- Analog RealTime Synthesiser. That doesn't interest me very much - I know, I know, sound is important, but not to me. Sorry. -

lftp: Tech Words the Day  
- A very sophisticated ftp/http/sftp command line client. It's very like ncftp, but is Open Source. Its history function works like Bash (ncftp is a bit different). It has a "mirror" function and even a reverse mirror. -

bashdb: Tech Words the Day  
- A better debugger for your Bash scripts: http://bashdb.sourceforge.net/. Actually, it replaces Bash, so if your script was particularly strange, you might exhibit a problem when it runs under bash -

snapshot: Tech Words the Day  
- A filesystem technique that allows leisurely backups while continuing to use the system. This magic is accomplished by making a special copy of a directory or filesystem (the exact mechanics will vary with the product you are using) that doesn't really copy anything unless and until data changes at the source. -

Fcheck: Tech Words the Day  
- Another IDS (intrusion detection system). Open sourced, though personally I find it a little scary that the author is hosting his website at Geocities. -

cfengine: Tech Words the Day  
- This is not something you deploy for the heck of it. Setup and preparation is complicated and may not be worth the effort if you only have a few systems. -

TCB, MAC, DAC: Tech Words the Day  
- Trusted Computing Base. The programs (more technically, objects and processess) that are trusted to do what they are supposed to do (and only what they are supposed to do). -

openMosix: Tech Words the Day  
- OpenMosix is transparent clustering - processes migrate to other members automagically. Project is closed as of March 1, 2008. -

autonomic computing: Tech Words the Day  
- It's more a matter of prejudice than a matter of definition; this is IBM's view of the future, which encompasses and goes beyond the 'self-healing' systems being talked about today. -

Why are in-addr.arpa addresses backwards?  
- An 'in-addr.arpa address' is a reverse DNS record, stored in a strange format. If we are considering ip 1.2.3.4, then '4.3.2.1.in-addr.arpa' is the reverse DNS record. -

winmodem: Tech Words the Day  
- A traditional hardware modem really is two major parts: the modulator/demodulator (hence 'modem') which translates the buzzes and hisses to bits and vice versa, and the 'personality': the hardware and software that lets you type AT commands, does error checking and all the rest. -

pagerank: Tech Words the Day  
- Primarily Google Pagerank, but could refer to any generic indication of site popularity. All of us who run web sites fret over popularity -

 
 
LOD Communications, Inc.
 
 
nat, masquerade: Tech Words the Day  
- Network Address Translation. Purists like to reserve this for the specific case of one to one mapping: one internal address to one external address. That usually means that you'll have a block of public addresses, though it doesn't mean that you need a public IP for every internal address. -

RBAC: Tech Words the Day  
- Terminology varies widely with specific implementations, but there will be some set of defined privileges or authorizations that can be assigned to certain users or processes -

dmidecode: Tech Words the Day  
- Dumps BIOS information. From http://www.nongnu.org/dmidecode/: ;Beware that DMI data have proven to be too unreliable to be blindly trusted. Dmidecode does not scan your hardware, it only reports what the BIOS told it to.' -

TLS: Tech Words the Day  
- The open incarnation of SSL. SSL (Secure Socket Layer) was the original encryption for web sessions, TLS (Transport Layer Security) does exactly the same thing but is open source. -

Howl: Tech Words the Day  
- Mac users familiar with Rendezvous know what Howl is: its Zeroconf networking. Open source, yes. -

VeRO: Tech Words the Day  
- Ebay's Verified Rights Owner's Program (gosh that's awful). The purpose of this is to allow manufacturers of products to prevent sales by unauthorized vendors. 'Naw', you protest, 'if I own it, surely I can sell it?'. Nope. -

Xorg: Tech Words the Day  
- Xorg replaces xfree86 for Linux gui now appears to be taking over - RedHat, IBM, Sun, Suse and Debian all are adopting it over Xfree86. While you will hear people arguing technical points, the reason behind this fork was political. -

XMPP: Tech Words the Day  
- The formal Extensible Messaging and Presence Protocol, which came from Jabber (open source IM). The important things to know about this are that it is XML based (and thus its messages are human readable if unencrypted, and it is easy to write code to handle these) and that it is extensible: new features can be added. -

Archie: Tech Words the Day  
- If you search around for definitions of Archie, you'll find out that it is a tool for searching for files from anonymous ftp servers. You'll probably also find comments like this: 'Back when FTP was the main way people moved files over the Internet archie was quite popular.' I would certainly agree with that - I haven't used archie in a long, long time. And yet, a Google search will turn up lots of Archie servers. -

Dvorak: Tech Words the Day  
- No, not John Dvorak the columnist, but Dr. August Dvorak, the inventor of the DSK (Dvorak Simplified Keyboard). Dvorak was actually following up on work by Frank Gilbreth, author of Cheaper by the Dozen. -

latency: Tech Words the Day  
- Basically, delay. Different from bandwidth, and the source of unending confusion and argument because of that. Latency affects everything from hard drives to the internet. -

Active Directory: Tech Words the Day  
- Microsoft's replacement for the awful Domain Controller concept. Two important things you need to understand here are that it is really LDAP, and that it is (or can be) distributed. -

N1 Grid Containers: Tech Words the Day  
- This is Sun's awful name for their server virtualization capability in Solaris 10. This lets you set up up to 4,000 virtual Solaris machines which use a common kernel (thus meaning one point for kernel patches,etc) but having their own IP address, memory, file area, host name, and root password. -

copyleft: Tech Words the Day  
- A generic term for open source licensing. Used to be common for websites; is not now. -

ZFS: Tech Words the Day  
- ZFS is supposed to be easier to comprehend and administer. I'm all for that: I have often complained that filesystems like Veritas (a former favorite of Sun) can be very difficult. I have yet to put up a Solaris 10 box so am not ready to agree that it is easy yet, but any improvement will be welcome. -

apmd: Tech Words the Day  
- The power management daemon for Linux. Very necessary for laptop users, it lets you shutoff services as power fades, thereby giving you more time to do whatever it is you do. Tip for laptop users: do you think you can just run out to Walmart and buy an extra battery and/or charger cable? Probably not.. -

Grass: Tech Words the Day  
- GRASS GIS (Geographic Resources Analysis Support System) http://grass.fbk.eu/. Map rendering, etc. Linux and many other platforms. Mac OSX port at http://openosx.com/grass/index.html -

Kino: Tech Words the Day  
- I don't even own a camcorder and can't imagine that I ever will, but if I did, I'd probably use a Mac for video editing. -

Catb: Tech Words the Day  
- Eric S. Raymond's 'The Cathedral & the Bazaar'. I couldn't find my copy - thought I had lent it to someone - and I wanted to read it again. Bummer. Happily, I spotted it mis-shelved just this morning. Read it again, and still don't understand why anyone but a fellow geek would enjoy this. And yet the popular press praised it. -

unionfs: Tech Words the Day  
- If you then mount some device on that directory, ordinarily, the original files would no longer be available, but a union mount leaves them visible. -

blosxom Blogging tool : Tech Words the Day  
- A simple Perl blogging tool. It doesn't require MySQL or really anything beyond the most basic Perl, so it is easy to plug in anywhere. It uses text files as its database, thus making it easy to interface with anything else. -

Yellow Dog Linux: Tech Words the Day  
- Linux for Macs. I thought this was near dead, but apparently not: http://www.yellowdoglinux.com/ announced version 4.0 (based on Fedora Core 2) in September 2004. -

PAM: Tech Words the Day  
- Pluggable Authentication Module. I think this is one of the all time best ideas ever. I do think it could use some polishing on the configuration side: it should be easier and less confusing, but the basic idea of flexible authentication is beautiful. -

LyX: Tech Words the Day  
- Lyx outputs LaTex. A GUI word processor that outputs LaTex files. Why would you want to do this? Probably if you had to share documents with someone who uses TEX but don't want the trouble of learning it. -

Linux|Unix Trace Toolkit: Tech Words the Day  
- Sometimes you want to trace a specific process, and strace does that nicely. But other times you want to see more about the whole system; that's LTT. -

regex: Tech Words the Day  
- Regular Expression. The type of pattern matching you do with sed or grep or Perl uses regexes. There are whole books on regular expressions. I imagine most of us have some degree of familiarity, but this can be a very complex subject. -

unison: Tech Words the Day  
- Unison is similar to rsync, and has a Windows version. There are binaries and ports available, but if you need or want to build this, you need an Objective Caml compiler -

rot13: Tech Words the Day  
- The most advanced encryption available today. OK, just kidding, but Julius Caesar's day, this was hot stuff. Nowadays, it's so well known that it's used just for things like protecting a jokes punchline, or hiding potentially offensive text until the reade decides they want to see it. -

Formmail: Tech Words the Day  
- Probably 'Matt's Formmail' though there are other scripts out there with the same name and purpose. Most webmasters will tell you that their http logs are filled with records indicating attempts to execute /cgi-bin/FormMail.pl -

AIDE: Tech Words the Day  
- A free replacement for tripwire. According to the source page - http://sourceforge.net/projects/aide - this caught a break in at debian.org. -

shar: Tech Words the Day  
- "shar" is a grown-up, steroid enhanced version of the "bundle" script from Kernigan and Pike's classic "Unix Programming Environment Handbook". -

 
 
 
 
amavis: Tech Words the Day  
- Amavis is a glue script that interfaces an MTA like sendmail, qmail, etc. with actual virus scanners. Because mail systems vary so much in their configuration, installing Amavis and whatever scanner you actually will use can be confusing. -

shtool: Tech Words the Day  
- Its primary intent is for use within installation scripts, it can also be useful for general scripting and is educational for learning portable shell scripting. -

strace, trace: Tech Words the Day  
- System Call Trace, strace on Linux, often just trace on other Unixes. I have used this tool many times to track down baffling application problems. For example, I recently had a client transfer Cobol programs from an old SCO system to Linux. -

cmp: Tech Words the Day  
- I often forget about 'cmp' and use 'diff' when all I really want to know is if two files are the same: cmp -s file1 file2 || echo 'Not the same' -

less: Tech Words the Day  
- As they say, less is more, both in terms of it having the same function and because it really is. -

pragma: Tech Words the Day  
- A directive to a compiler or interpreter that tells it something about how it should do its job. It's not part of your program per se, though it may affect the final result. -

see: Tech Words the Day  
- A useful Debian tool that lets you "see" compressed files without uncompressing them. -

alien: Tech Words the Day  
- Convert Debian .deb to RedHat RPM: http://www.kitenet.net/programs/alien/. It's a Perl script. Converting can be just the beginning of chasing down dependencies, so don't expect that this just lets you automatically use Debian packages. -

honeyd: Tech Words the Day  
- A honeypot that uses separate scripts for the services you want to trap. I couldn't make it work on a brand new RedHat system. -



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