Friday, October 26, 2007

Alienware Area-51 m9750 Review

There was a time when if you wanted to play games you didn't buy a notebook. Notebooks were fine for spreadsheets and shopping lists, but fire up an up-to-date 3D game and you were entering a world of painfully slow frame rates. It's all different these days of course, with everyone from the likes of Rock, Evesham and Dell offering pimped out powerhouses designed to give you portable gaming pleasure that you can easily slip into a cupboard when you're done. If that's the sort of thing that appeals then you really can't buy without considering Alienware. It prides itself on producing gaming PCs and notebooks for the masses and based on previous efforts, we know it does a pretty darn good job. Inevitably, a fully loaded Alienware system is going to cost the proverbial arm and leg, but it's still always going to be more affordable than truly custom boutique suppliers of true exotica such as Vadim. After all, this is a company owned by Dell.

Good news then that Alienware has launched a new top-of-the-range gaming notebook. The system we were sent was pretty loaded specification wise, which accounts for the full on £2,462 price tag, compared to the rather less eye watering £1,198 that the system starts at. Coming under the Area-51 umbrella, our sample m9750 features an Intel Core 2 Duo T7600 running at 2.33GHz, backed up with 2GB of 667 RAM. This is combined with nVidia SLI graphics. Just to be clear, SLI is nVidia's dual graphics card technology, so you're not just getting one GeForce Go 9750 GTX in this notebook, you're getting two. In case you're not up on your graphics technology, that’s a good thing, potentially offering up to twice the performance in certain games. Along with this you're getting two hard disks, which can be set up in RAID 0 or 1 configuration offering either 250GB of secure storage or 500GB of ultra fast storage. You also get a 1,920 x 1,200 resolution display, which is quite something on a 17in display - you won't see this resolution on anything smaller than a 23in external monitor.

There are two aspects to the Alienware that make it stand out when you first see it; its physical size and its design. It's actually quite compact for a notebook with a 17in screen - I guess black really is slimming. The traditional Alienware ribbed effect is present on the notebook lid along with the Alien head and I was delighted to see the squinty eyes light up blue when the notebook is powered on. I know it's rather shallow to be impressed by such small things but then it's the little things that make the difference. If you want your machine to stand out from the crowd at Lan party or when friends come over, this will do the trick. It's not just the look, but the feel too. The new 'Stealth Black' finish is well named, not only looking good but having a slightly weird absorbent, slightly oily feel to it. If Alienware claimed that the m9750 was radar resistant, I'd probably believe it.

There's a substantial clip holding down the lid, which once dealt with lifts up to reveal a magnificent 17in, 1,920 x 1,200 display. The bezel has a shiny finish to it and is adorned with the Alienware logo. There's also a adjustable 1.3 megapixel webcam at the top.

The 1,920 x 1,200 resolution is really something, giving plenty of desktop real estate and making this a real contender as a desktop replacement. A possibly downside is that squeezed into a 17in display text at normal sizes can be quite small, so you may have to zoom up at times. But let's face it, this is a notebook aimed at entertainment, not shopping lists or boring spreadsheets, though it will of course be pretty good for those as well. In pure quality terms the screen is good. It's averagely bright but perfectly sharp, and its 'Clearview' coating gives it a high gloss sheen, effectively boosting colour and contrast. It also boosts reflections too though, and if you're working in front of it for extended periods in a brightly lit environment, say the TrustedReviews office, then it could prove distracting. If you're locked into a dark secluded gaming dungeon however, this screen will be right in its element.

As you might expect, beneath the screen you'll find the keyboard. In an elegant touch I liked the way the area containing the hinges for the screen curve upwards. Beneath this you'll find shortcut keys for the usual suspects such as your web browser, your mail program and your media player. There's also a TV button, which makes sense as there's an integrated TV tuner to make the most of Vista's built-in Media Center software. Above these there's a row of blue backlight indicators for wireless, charging, hard disk activity and if the mouse pad is active, as well as scroll and number lock. Of course the power button of the right of this has a cool blue light too.

You get a pretty much full size keyboard with a number pad too. It does mean that when you’re sitting in front of it you're shifted slightly over to the side, but it's not as bad as some I've used. You get a full size Backspace, Right-Shift and Return key, and arrow keys underneath, but the Home, Page Up/Down and End keys are also located on the arrow keys and you have to use the Function key to get to them. The keys have a good feel to them but I did want a touch more travel to them - not a deal breaker though. The touch pad is a large oblong affair, to match the aspect ratio of the screen, and there's a scroll area on the right of it.

At the front edge of the notebook you'll find the optical drive - an 8-speed dual-layer DVD burner. On either side you'll find the speakers, which are well placed to project audio into the room. Volume level was pretty decent and would suffice for gaming or watching movies.

On the left hand edge you'll find an Express card slot - not PC Card, and a memory card reader. You'll also find one mini Firewire port, a USB port and a Gigabit Ethernet socket and right in the corner a security hook, should you need to keep it locked down. On the opposite side you'll find one more USB port, and all the audio sockets, headphone and microphone and line outs for front, centre, surround coming from the integrated Intel High Definition Audio chip to give you 7.1 when hooked up to a compatible speaker set. If you prefer to output digitally to an amplifier, there's an optical port. There's also an analogue volume wheel, though I found it was a little insensitive requiring far too much scroll to reach the desired level.

At the rear you'll find DVI and VGA connectors and a hybrid TV tuner, giving you either analogue or digital, but not both. There's an S-Video input to accompany this and audio in for connecting up a set-top box. There's a final USB port, taking the count up to three and even a modem connector. The power input is right in the centre, which is unusual and kind of cool.

One aspect that should be noted is that Alienware has made no pretensions at making this a Santa Rosa machine - there's no Santa Rosa CPU, no Turbo Memory, no Draft-N wireless. But as we've found that at least one of these is missing from most supposedly Santa Rosa machines we've looked at, I'm not all that disappointed.

Having a 1,920 x 1,200 resolution display on a gaming notebook often doesn't make all that much sense, but there is some logic to it, when you're pairing it with SLI graphics. The dual GeForce 7950s have required some real work done on the design to deal with the increased heat output and if you put your hand behind the rear exhaust when it's in full flow and your can really feel it. What's impressive though is that even when playing games the machine is surprisingly quiet and it doesn't get outrageously hot.

To be honest at first it seemed difficult to be amazed at the dual 7950s, as when it comes to desktop graphics the GeForce 7-series is yesterday's news. As ever, what was the fastest a few months ago seems tired all too soon. But the reality is that dual 7950s is still the fastest things available in mobile graphics on the planet, so it does deserve our respect. More than just raw speed though, the GeForce 7 series lags behind the 8-series in terms of features and quality - being Direct X 9, not 10 and offering less hardware acceleration for H.264 video processing. Real areas where this might an issue are if you want to run with HDR and anti-aliasing at the same time, or play games such as Lost Planet with the best effects possible. In testing I also found that the machine dropped frames when playing 1080p Quicktime trailers encoded in H.264, which was a bit of a shame.

While this was slightly disappointing, it was offset by firing up Oblivion, which over a year since its release is still one of the most demanding tests to which you can put a gaming rig. The m9750 passed this test admirably, which is something beyond most laptops. I played with very high graphical settings at the native resolution and achieved around 30fps in quiet scenes. It did stutter a little when the swords came out and the action heated up, so you would need to take the graphical settings down a little but if you do you'll get a great gaming experience. If you play a less demanding title you should have no problems at all. The high resolution on a relatively small screen produced produced a smooth, clear image that looked just fabulous.

Still, with DX10 games such as Crysis looming the 7950s could seem to be a limitation so I was relieved to confirm that Alienware will offer an upgrade path to mobile 8800s when they appear, though there is absolutely no information at present on when this might be or how much it might cost. It’s vital to know this though, as if you’re going to spend around £2,500 you need to know that your investment won’t be completely obsolete by the end of the year.

Along with two cores in the CPU, and two GPUs, this fully loaded machine also sports two hard disks, both offering 250GB of hard disk capacity. This means that you can set up RAID 0 or RAID 1 configuration - for extra capacity and speed, versus security - it's your choice. If you go for RAID 0 – that’s 500GB – not bad for a notebook, though we’d recommend an external backup, as with two disks there’s two points of potential failure. The disks provided were spinning at 5,400rpm though faster 7,200rpm models are available. When we received our review sample, SLI drivers for Vista were not ready so Alienware shipped the machine to us with Vista on one disk and XP on another. As a result our 3D tests are done in XP. However, Vista SLI drivers are here so that’s what all shipping machines will have.

When it came to performance we had to decide what to compare the machine to. In laptop terms it’s pretty much out there on its own but we felt that the Shuttle SD39P2 system that I looked at recently was a good candidate. After all, aside from a laptop, if you’re looking for a compact system a Shuttle would be the way to go. The luxury a Shuttle gives you is the ability to put a full-on GeForce 8800 GTX inside, As such, in performance terms the Alienware is soundly beaten on the raw numbers front, which hurts it considering that the Shuttle is also a lot cheaper to put together, even if you add the cost of a 24in monitor and speakers.

In raw performance terms then, the Alienware doesn’t make sense – but what you have to take into account is its portability. Sure, 3.9Kg is not light, but you can’t fold up a Shuttle and place it in a draw or carry it around anywhere nearly as easily. The looks and design are also on a different planet. I actually don’t see this machine as quite the complete package – I’d have liked to have seen a dual digital TV Tuner for a start, but it’s still the best gaming laptop I’ve seen. The dual 7950 GTX cards can and will deliver an excellent gaming experience and when the mobile 8800 series do eventually arrive this machine could be something very special indeed. There’s no denying that there’s still ultimately a compromise to be made between portability and performance but the fact that you’ve got an upgrade path if you buy now makes this still an enticing prospect on two conditions – you really want a laptop over a compact desktop and you’ve got the funds to fuel your desire.


Alienware has done its reputation no harm with this wonderfully designed and great looking beast of a machine. Two cores in the CPU, two GeForce 7950 GTX GPUs and two hard disks, along with a TV Tuner, 7.1 output and decent speakers, make it a superb entertainment machine. Sure you can build a faster desktop for less, but for ultimate portable power this Alienware is on another planet.

Author : Benny Har-Even

Bell picks up LG Shine, if you can really call it that

'Round here, we think of a slider when you tell us so-and-so is launching the LG Shine, but Bell apparently has something a little different in mind. Canadians can now pick up the metal-clad Shine flip (again -- Bell's name, not ours) for a cool $130 CAD (about $134) on a three-year contract, offering the same EV-DO data, 2 megapixel cam, A2DP, and funky sideways external display as its VX8700 cousin on Verizon. For Bell's sake, we hope they don't go launching a Shine slider down the road -- 'cause what the heck are you going to call that then? Hmm?

By Chris Ziegler

Nokia and Reuters...

Nokia and Reuters develop an N95-based "Mobile Journalism Toolkit"

The rise of the cameraphone has certainly changed the face of journalism, and old-guard wire service Reuters isn't about to get passed by -- the company has entered into a long-term partnership with Nokia to develop new mobile reporting technologies, and the two companies have recently completed trials of an N95-based "Mobile Journalism Tookit" that takes moblogging to a whole new level. Reporters were given a hardware bundle that consisted of an N95, a Nokia SU-8W portable keyboard, a Sony condenser mic with special N95 adapter, a tripod, and two Power Monkey power stations, including the solar-capable Explorer, all of which linked into a custom mobile CMS that allows stories to be posted almost instantly. Reuters also partnered with Comvu for GPS-linked video streaming, and the N95 also provides a host of other metadata about each piece of content as it's filed. Although the trial is now over, both Reuters and Nokia plan on using the kits to teach journalism students and to promote the cause of citizen journalism. Let's hope that means they start teaching people how to take non-blurry cameraphone spy shots, eh?

by Nilay Patel

Thursday, October 25, 2007


iPhone review

The first solid info anyone heard about the iPhone was in December of 2004, when news started to trickle out that Apple had been working on a phone device with Motorola as its manufacturing partner. About ten months later, under the shadow of the best-selling iPod nano, that ballyhooed device debuted -- the ROKR E1 -- a bastard product that Apple never put any weight behind, and that Motorola was quick to forget. The relationship between Apple and Motorola soon dissolved, in turn feeding the tech rumor mill with visions of a "true iPhone" being built by Apple behind the scenes. After years of rumor and speculation, last January that device was finally announced at Macworld 2007 -- and here we are, just over six months later -- the iPhone, perhaps the most hyped consumer electronics device ever created, has finally landed. And this is the only review of it you're going to need.

The hardware

Industrial design

We're just going to come out and say it: the iPhone has the most beautiful industrial design of any cellphone we've ever seen. Yes, it's a matter of taste, and while we imagine some won't agree, we find it hard to resist the handset's thoughtful minimalism and attention to detail.

The edges of the beautiful optical-grade glass facade fit seamlessly with its stainless steel rim; the rear is an incredibly finely milled aluminum, with a hard, black plastic strip at the bottom, covering the device's antenna array, and providing small, unsightly grids of holes for speaker and mic audio. On the rear is the slightly recessed 2 megapixel camera lens, a reflective Apple logo, and some information about the device (IMEI, serial, etc.) in nearly microscopic print. (Sorry, iPhone engravings don't seem to be available yet for online customers.)

The iPhone's curves and geometry make it incredibly comfortable to hold. It fits well in the hand horizontally and vertically (completely one-handed operation is a snap in portrait mode), and its slim profile lets it slip into even a tight pocket with little effort. The device feels incredibly sturdy and well balanced -- no end seems any heavier than another. Every edge blends perfectly with the next (which will probably help fight gunk buildup over time), and holding the device to one's ear is comfortable enough, although not as comfortable as, say, the HTC Touch.

Our only real complaint with the device's design isn't one we take lightly: Apple went to the trouble of giving the iPhone a standard 3.5mm headphone jack, but the plug is far too recessed to use most headphones with -- we tested a variety, and were highly unimpressed with how many fit. What's the point of a standard port if it's implemented in a non-standard way? Apple might have at least included an extender / adapter for this, but didn't. Luckily, the iPhone earbuds sound very decent, and also include a minuscule, clicky in-line remote / mic -- but that's not going to alleviate the annoyance for the myriad users with expensive Etys or Shures who have to pay another $10 for yet another small part to lose.

The display

The iPhone features the most attractive display we've ever seen on a portable device of this size, by far and bar none. While its 160ppi resolution isn't quite photorealistic, the extremely bright 3.5-inch display does run at 480 x 320, making it one of the highest pixel-density devices around today (save the Toshiba G900's mind-popping 3-inch 800 x 480 display). But pixel density doesn't necessarily matter, it's how your device uses the screen real estate it's got. Instead of printing microscopic text, as Windows Mobile often does with high resolution displays (see: HTC's Universal and Advantage), iPhone text looks smooth and natural in every application -- everything on-screen is eminently readable.

The screen also provides an excellent outdoor viewing experience. With optical properties reminiscent of transflective displays, the iPhone remains completely readable (if a only bit washed out) even in direct sunlight. Unfortunately, the display's viewing angle left a little something to be desired, and the rumors about the glass face being an absolute fingerprint magnet are totally true: this thing picks up more smudges than almost any touchscreen device we've ever used. Honestly though, we'd attribute this to the fact that unlike most other smartphones, you are exempt from using a stylus on the iPhone's capacitive display, meaning you must touch it with your bare finger to do almost anything.

Thankfully, like the rest of the phone, the glass face feels extremely sturdy, and one should have absolutely no hesitation in wiping it off on their jeans or sleeve -- we've yet to produce a single scratch on the thing, and we understand others testing under more rigorous circumstances (like deliberately trying to key its face up) have also been unable to mar its armor.

The sensors
One of the more unique features in the iPhone is its trio of sensors (orientation, light, and proximity -- the latter two are behind the glass right above the earpiece) which help the device interact with its user and the world at large. Some of these sensors are more useful than others. The light sensor (for dimming the backlight) is great for saving power, but its use doesn't compare to the the other two sensors, which worked like champs. The proximity sensor, which prevents you from accidentally interacting with the screen while the iPhone is pressed against your ear, switches off the display at about 0.75-inches away; the screen switches back on after you pull away about an inch. This very useful automatic process took a little getting used to from us oldschool touchscreen users, who have long since grown accustomed to diligently turning off the screen while on a call, or holding our smartphones to our ear ever so gently.

The orientation sensor also worked well enough. Although you can't turn the phone on its head, when browsing in Safari you can do a 180, jumping quickly from landscape left to landscape right. The iPhone would occasionally find itself confused by the odd angles one sometimes carries and holds devices at, but in general we didn't expect the orientation sensor to work as well as it did.

Button layout

Despite the iPhone's entirely touchscreen-driven interface, all of its external buttons are mechanical and have a distinct, clicky tactility. There is, of course, the home button on the face, which takes you back to the main menu; along the left side of the unit is the volume up / down rocker (which is clearly identifiable by touch), and a ringer on / off switch -- something we wish all cellphones had, but that far too few actually do. Turning off the ringer briefly vibrates the device to let the user know rings are off; it's worth noting that turning the ringer off doesn't turn off all device audio, so if you hit play on a song in iPod mode, audio will still come out the speaker if you don't have headphones inserted.

On the top of the unit is the SIM tray (each unit comes pre-packaged with an AT&T SIM already inserted), which pops out by depressing an internal switch with a paperclip. Finally, the largest perimeter button is the sleep / wake switch, which does as you'd imagine. Press it (and swipe the screen) to wake up the device, or press it to put it to sleep; hold it (and swipe the screen) down to shut it off completely. (You can also use it turn off the ringer - -one click -- or shunt a call to voicemail -- two clicks -- if someone rings you.)

The headphones

The iPhone comes bundled with a standard set of iPod earbuds, but there are two differences from the kind that comes with your regular old iPod. First, these earbuds don't have the small plastic cable separator slide that helps keep your cables from getting tangled. Second, on the right channel cable about halfway up you'll find a very slim, discreet mic / music toggle. When listening to music, click it once to pause, or twice to skip tracks; when a call comes through, click it once to pick up, and again to hang up.

That same in-line piece also picks up your voice for the call, and it sounds pretty good -- some people on the other end of the line said it sounds even better than the iPhone's integrated mic. For those worried that there would be issues with interference, put your mind at ease. We heard absolutely no cell radio interference over the headset, even when we wrapped it four times around the iPhone antenna, and sandwiched it between a second cellphone making a call. The headphones are an essential and amazing accessory that makes the seamless media and phone experiences of the device possible. We only wish Apple managed to integrate an inline volume switch in there too, since that's really the only essential control it lacks.

Unfortunately for us, iPod headphones just don't fit our ears, so no matter how good they may sound, they're unusable since we can't seem keep them in longer than 30 seconds. (We typically prefer canalphones, they can't really go anywhere.) Since the included headphones are the only ones on the market right now that can interact with the iPod function, have an inline mic, and, of course, listen to audio, you're kind of stuck with Apple's buds if you want to get the most out of your iPhone. The same also applies to the expensive phones you invested in, which probably won't fit in the recessed jack anyway: even if you get an adapter, you still won't get the full experience.

Apple's included headphones are about 42-inches long (3.5 feet), just about the perfect length to reach from your pocket to your head with a little extra slack. You'd be surprised how many cellphone manufacturers screw this up with bundled headphones that are way too long, or way too short.

The dock, charging

The included dock is up to par for Apple's typically high standards -- it feels very solid and sturdy with no visible mold lines, and is capped on the bottom by a solid rubber base (with a nearly hidden vent for letting sound in and out of the iPhone's speaker and mic) to keep it in place. On its rear is the usual cable connector and line out. We thought the dock props the iPhone way too vertically -- about 80°, significantly more upright than the stock iPod dock we compared it to. If you're using it on a desk, you'll probably wish Apple angled it back a little so you're not leaning over to fumble with your phone like some miniature monolith.

Charging the iPhone is an easy enough affair. Pulling power from its adapter (and not a computer's USB), we were able to quick-charge it from 0% to 90% in just under two hours, but it took us almost another hour and a half to get that last ten percent. We also twice ran into this weird bug, where charging the iPhone from 0% power would deactivate the screen. The only way to recover was to soft-reset the phone. No big deal, just irritating. It's probably also worth mentioning that going from totally shut off to fully booted, the iPhone is up and running in under 30 seconds.

Other accessories
Apple also includes a microfiber polishing cloth -- a welcome addition, but the device's sturdy glass will stand up to rubs on most of your clothes, so don't bother carrying it along if you're planning to just brush off some dust or residue left by your face / ears / fingers, etc. Also included is an extremely small power brick, and USB connector cable. Worth noting: the iPhone connector cable doesn't include tensioned clips, like most iPod connectors -- just pull it out, nothing messy to get caught and broken, and fewer moving parts in general.

User interface

If there's anything revolutionary, as Apple claims, about the iPhone, it's the user interface that would be nominated. Countless phones make calls, play movies and music, have maps, web browsers, etc., but almost none seem able to fully blend the experience -- which is part of the reason people flipped out at the idea of an iPhone. The device's user interface does all this with panache, but it's not without a number of very irritating issues. Before we get into those issues, however, we should quickly rundown the functions of the iPhone's primarily gesture-based input system.

iPhone gestures
Drag - controlled scroll up / down through lists
Flick - quickly scrolls up / down through lists
Stop - while scrolling, tap and hold to stop the moving list
Swipe - flick from left to right to change panes (Safari, weather, iPod) and delete items (mail, SMS)
Single tap - select item
Double tap - zooms in and out (all apps), zooms in (maps)
Two-finger single tap - zooms out (maps only)
Pinch / unpinch - zoom in and out of photos, maps, Safari

As you can probably already tell, gestures in the iPhone are by no means consistent. By and large one can count on gestures to work the same way from app to app, but swipes, for example, will only enable the delete button in mail and SMS -- if you want to delete selected calls from your call log, a visual voicemail message, world clock, or what have you, you've got to find another way. Swiping left to right takes you back one pane only in iPod, and two-finger single tap only zooms out in Google maps -- none of the other apps that use zooming, like Safari, and photos.

These kinds of inconsistencies are worked around easily enough, but add that much more to the iPhone learning curve. And yes, there is definitely a learning curve to this device. Although many of its functions are incredibly easy to use and get used to, the iPhone takes radically new (and often extremely simplified and streamlined) approaches to common tasks for mobile devices.

Another rather vexing aspect of the iPhone's UI is its complete inability to enable user-customizable themes -- as well as having inconsistent appearances between applications. Users can set their background (which shows up only during the unlock screen and phone calls), but otherwise they're stuck with the look Apple gave the iPhone, and nothing more. This is very Apple, and plays right into Steve's reputation as a benevolent dictator; he's got better taste than most, but not much of a penchant for individuality.

Even still, Apple's chosen appearance varies from app to app. Some apps have a slate blue theme (mail, SMS, calendar, maps, Safari, settings), some have a black theme (stocks, weather), some have a combination blue / black theme (phone, iPod, YouTube, clock), some have a straight gray theme (photos, camera), and some have an app-specific theme (calculator, notes). Even the missing-data-background is inconsistent: checkerboard in Safari, line grid in Google maps. There's little rhyme or reason in how or why these three themes were chosen, but unlike OS X's legacy pinstripes and brushed metal looks, there's really no reason why the iPhone should have an inconsistent appearance between applications.


Since its announcement, the iPhone's single biggest x-factor has been its virtual keyboard -- primarily because the quality of its keyboard can make or break a mobile device, and of the numerous touchscreen keyboards released over the years, not one has proven a viable substitute for a proper physical keyboard. We've been using the keyboard as much as possible, attempting to "trust" its auto-correction and intelligent input recognition, as Apple urges its users to do in order to make the transition from physical keys. (The iPhone uses a combination of dictionary prediction and keymap prediction to help out typing.)

The whole idea of a touchscreen is a pretty counterintuitive design philosophy, if you ask us. Nothing will ever rid humans of the need to feel physical sensations when interacting with objects (and user interfaces). Having "trust" in the keyboard is a fine concept, and we believe it when people say they're up to speed and reaching the same input rates as on physical keyboards. But even assuming we get there, we know we'll always long for proper tactile feedback. That said, we're working on it, and have found ourselves slowly growing used to tapping away at the device with our stubby thumbs.

As for the actual process of typing, one hindrance we've had thus far is that despite being a multi-touch system, the keyboard won't recognize a second key press before you've lifted off the first -- it requires single, distinct key presses. But the worst thing about the keyboard is that some of the methods it plies in accelerating your typing actually sacrifice speed in some cases. For example, there is no period key on the main keyboard -- you have to access even the most commonly used symbols in a flipped over symbols keyboard. This is almost enough to drive you crazy. (We really, REALLY wish Apple would split the large return button into two buttons: one for return, one for period.)

Caps lock is also disabled in the system by default, but even if you enable it in settings (and then double-tap to turn it on), you still can't hold down shift for the same effect -- it's either caps on, or you have to hit shift between each letter. Also, whether you're in upper or lower case, the letters on the keyboard keys always look the same: capitalized. (This makes it difficult to see at a glance what case of text you're about to input, especially since when using two thumbs your left thumb always hovers over the shift key.) Oh, and don't hit space when typing out a series of numbers, otherwise you'll get dropped back into the letter keyboard again.

We also found the in-line dictionary tool to be more cumbersome than helpful. Supposedly, to add a word that's not in the dictionary, type in your word, then when you get an autocorrect value, just press on that word and the word you typed will be added to the dict file (uhh, ok). But you can also accidentally add words to your dictionary by typing out a word, dismissing the autocorrect dropdown by adding another letter, then backspacing over it. Yeah, for some reason that adds a word to the dictionary file, too. And believe it or not, this confusing little problem caused us to add a number of bum words to the dict file (which you can only keep or clear in its entirety -- and no you can't back it up, either).

On the up side, the horizontal keyboard (which is only enabled when typing into Safari while browsing horizontally) is a much more palatable experience. The keys are far larger, resulting in drastically fewer typing mistakes. (We sincerely hope Apple will enable horizontal input for all its iPhone apps that require keyboard input.) The horizontal web keyboard also has very convenient previous / next buttons for tabbing through fields. The keyboard you're given when entering URLs is one of the most brilliant bits we've seen in the device, and is an incredible time-saver. Since there are almost never spaces in URLs, instead users have shortcuts to ".", "/", and ".com". Finally, the magnification loupe is the best touchscreen cursor positioning method we've seen to date in a mobile device. Too bad you can't highlight and cut / copy / paste text with the iPhone.

So what's the long and short of the keyboard story? We're still getting used to it, but for a touchscreen keyboard it could have been a lot worse -- and a whole lot better. Some among the Engadget staff have been able to pick it up quickly, others, not so much -- your mileage may vary. We have to wonder though, what would it take to get Steve to give us a proper physical keyboard for this mother, anyway? (We already smell the cottage industry brewing.)

by: Ryan Block

Tuesday, October 23, 2007

UNIX Introduction

What is UNIX?

UNIX is an operating system which was first developed in the 1960s, and has been under constant development ever since. By operating system, we mean the suite of programs which make the computer work. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops.

UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy to use environment. However, knowledge of UNIX is required for operations which aren't covered by a graphical program, or for when there is no windows interface available, for example, in a telnet session.

Types of UNIX

There are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X.

Here in the School, we use Solaris on our servers and workstations, and Fedora Core Linux on the servers and desktop PCs.

The UNIX operating system

The UNIX operating system is made up of three parts; the kernel, the shell and the programs.

The kernel

The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls.

As an illustration of the way that the shell and the kernel work together, suppose a user types rm myfile (which has the effect of removing the file myfile). The shell searches the filestore for the file containing the program rm, and then requests the kernel, through system calls, to execute the program rm on myfile. When the process rm myfile has finished running, the shell then returns the UNIX prompt % to the user, indicating that it is waiting for further commands.

The shell

The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell. The shell is a command line interpreter (CLI). It interprets the commands the user types in and arranges for them to be carried out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems).

The adept user can customise his/her own shell, and users can use different shells on the same machine. Staff and students in the school have the tcsh shell by default.

The tcsh shell has certain features to help the user inputting commands.

Filename Completion - By typing part of the name of a command, filename or directory and pressing the [Tab] key, the tcsh shell will complete the rest of the name automatically. If the shell finds more than one name beginning with those letters you have typed, it will beep, prompting you to type a few more letters before pressing the tab key again.

History - The shell keeps a list of the commands you have typed in. If you need to repeat a command, use the cursor keys to scroll up and down the list or type history for a list of previous commands.

Files and processes

Everything in UNIX is either a file or a process.

A process is an executing program identified by a unique PID (process identifier).

A file is a collection of data. They are created by users using text editors, running compilers etc.

Examples of files:

  • a document (report, essay etc.)
  • the text of a program written in some high-level programming language
  • instructions comprehensible directly to the machine and incomprehensible to a casual user, for example, a collection of binary digits (an executable or binary file);
  • a directory, containing information about its contents, which may be a mixture of other directories (subdirectories) and ordinary files.

The Directory Structure

All the files are grouped together in the directory structure. The file-system is arranged in a hierarchical structure, like an inverted tree. The top of the hierarchy is traditionally called root (written as a slash / )

Unix File Structure

In the diagram above, we see that the home directory of the undergraduate student "ee51vn" contains two sub-directories (docs and pics) and a file called report.doc.

The full path to the file report.doc is "/home/its/ug1/ee51vn/report.doc"

Starting an UNIX terminal

To open an UNIX terminal window, click on the "Terminal" icon from the drop-down menus.

Gnome Menus

An UNIX Terminal window will then appear with a % prompt, waiting for you to start entering commands.

Unix Terminal window

UNIX Chapter 1

1.1 Listing files and directories

ls (list)

When you first login, your current working directory is your home directory. Your home directory has the same name as your user-name, for example, ee91ab, and it is where your personal files and subdirectories are saved.

To find out what is in your home directory, type

% ls

The ls command lists the contents of your current working directory.

Unix Terminal - running the ls command

There may be no files visible in your home directory, in which case, the UNIX prompt will be returned. Alternatively, there may already be some files inserted by the System Administrator when your account was created.

ls does not, in fact, cause all the files in your home directory to be listed, but only those ones whose name does not begin with a dot (.) Files beginning with a dot (.) are known as hidden files and usually contain important program configuration information. They are hidden because you should not change them unless you are very familiar with UNIX!!!

To list all files in your home directory including those whose names begin with a dot, type

% ls -a

As you can see, ls -a lists files that are normally hidden.

Unix Terminal - running the ls command

ls is an example of a command which can take options: -a is an example of an option. The options change the behaviour of the command. There are online manual pages that tell you which options a particular command can take, and how each option modifies the behaviour of the command. (See later in this tutorial)

1.2 Making Directories

mkdir (make directory)

We will now make a subdirectory in your home directory to hold the files you will be creating and using in the course of this tutorial. To make a subdirectory called unixstuff in your current working directory type

% mkdir unixstuff

To see the directory you have just created, type

% ls

1.3 Changing to a different directory

cd (change directory)

The command cd directory means change the current working directory to 'directory'. The current working directory may be thought of as the directory you are in, i.e. your current position in the file-system tree.

To change to the directory you have just made, type

% cd unixstuff

Type ls to see the contents (which should be empty)

Exercise 1a

Make another directory inside the unixstuff directory called backups

1.4 The directories . and ..

Still in the unixstuff directory, type

% ls -a

As you can see, in the unixstuff directory (and in all other directories), there are two special directories called (.) and (..)

The current directory (.)

In UNIX, (.) means the current directory, so typing

% cd .

NOTE: there is a space between cd and the dot

means stay where you are (the unixstuff directory).

This may not seem very useful at first, but using (.) as the name of the current directory will save a lot of typing, as we shall see later in the tutorial.

The parent directory (..)

(..) means the parent of the current directory, so typing

% cd ..

will take you one directory up the hierarchy (back to your home directory). Try it now.

Note: typing cd with no argument always returns you to your home directory. This is very useful if you are lost in the file system.

1.5 Pathnames

pwd (print working directory)

Pathnames enable you to work out where you are in relation to the whole file-system. For example, to find out the absolute pathname of your home-directory, type cd to get back to your home-directory and then type

% pwd

The full pathname will look something like this -


which means that ee51vn (your home directory) is in the sub-directory ug1 (the group directory),which in turn is located in the its sub-directory, which is in the home sub-directory, which is in the top-level root directory called " / " .

Unix File structure

Exercise 1b

Use the commands cd, ls and pwd to explore the file system.

(Remember, if you get lost, type cd by itself to return to your home-directory)

1.6 More about home directories and pathnames

Understanding pathnames

First type cd to get back to your home-directory, then type

% ls unixstuff

to list the conents of your unixstuff directory.

Now type

% ls backups

You will get a message like this -

backups: No such file or directory

The reason is, backups is not in your current working directory. To use a command on a file (or directory) not in the current working directory (the directory you are currently in), you must either cd to the correct directory, or specify its full pathname. To list the contents of your backups directory, you must type

% ls unixstuff/backups

~ (your home directory)

Home directories can also be referred to by the tilde ~ character. It can be used to specify paths starting at your home directory. So typing

% ls ~/unixstuff

will list the contents of your unixstuff directory, no matter where you currently are in the file system.

What do you think

% ls ~

would list?

What do you think

% ls ~/..

would list?


Command Meaning
ls list files and directories
ls -a list all files and directories
mkdir make a directory
cd directory change to named directory
cd change to home-directory
cd ~ change to home-directory
cd .. change to parent directory
pwd display the path of the current directory

UNIX Chapter 2

2.1 Copying Files

cp (copy)

cp file1 file2 is the command which makes a copy of file1 in the current working directory and calls it file2

What we are going to do now, is to take a file stored in an open access area of the file system, and use the cp command to copy it to your unixstuff directory.

First, cd to your unixstuff directory.

% cd ~/unixstuff

Then at the UNIX prompt, type,

% cp /vol/examples/tutorial/science.txt .

Note: Don't forget the dot . at the end. Remember, in UNIX, the dot means the current directory.

The above command means copy the file science.txt to the current directory, keeping the name the same.

(Note: The directory /vol/examples/tutorial/ is an area to which everyone in the school has read and copy access. If you are from outside the University, you can grab a copy of the file here. Use 'File/Save As..' from the menu bar to save it into your unixstuff directory.)

Exercise 2a

Create a backup of your science.txt file by copying it to a file called science.bak

2.2 Moving files

mv (move)

mv file1 file2 moves (or renames) file1 to file2

To move a file from one place to another, use the mv command. This has the effect of moving rather than copying the file, so you end up with only one file rather than two.

It can also be used to rename a file, by moving the file to the same directory, but giving it a different name.

We are now going to move the file science.bak to your backup directory.

First, change directories to your unixstuff directory (can you remember how?). Then, inside the unixstuff directory, type

% mv science.bak backups/.

Type ls and ls backups to see if it has worked.

2.3 Removing files and directories

rm (remove), rmdir (remove directory)

To delete (remove) a file, use the rm command. As an example, we are going to create a copy of the science.txt file then delete it.

Inside your unixstuff directory, type

% cp science.txt tempfile.txt
% ls
% rm tempfile.txt
% ls

You can use the rmdir command to remove a directory (make sure it is empty first). Try to remove the backups directory. You will not be able to since UNIX will not let you remove a non-empty directory.

Exercise 2b

Create a directory called tempstuff using mkdir , then remove it using the rmdir command.

2.4 Displaying the contents of a file on the screen

clear (clear screen)

Before you start the next section, you may like to clear the terminal window of the previous commands so the output of the following commands can be clearly understood.

At the prompt, type

% clear

This will clear all text and leave you with the % prompt at the top of the window.

cat (concatenate)

The command cat can be used to display the contents of a file on the screen. Type:

% cat science.txt

As you can see, the file is longer than than the size of the window, so it scrolls past making it unreadable.


The command less writes the contents of a file onto the screen a page at a time. Type

% less science.txt

Press the [space-bar] if you want to see another page, and type [q] if you want to quit reading. As you can see, less is used in preference to cat for long files.


The head command writes the first ten lines of a file to the screen.

First clear the screen then type

% head science.txt

Then type

% head -5 science.txt

What difference did the -5 do to the head command?


The tail command writes the last ten lines of a file to the screen.

Clear the screen and type

% tail science.txt

Q. How can you view the last 15 lines of the file?

2.5 Searching the contents of a file

Simple searching using less

Using less, you can search though a text file for a keyword (pattern). For example, to search through science.txt for the word 'science', type

% less science.txt

then, still in less, type a forward slash [/] followed by the word to search


As you can see, less finds and highlights the keyword. Type [n] to search for the next occurrence of the word.

grep (don't ask why it is called grep)

grep is one of many standard UNIX utilities. It searches files for specified words or patterns. First clear the screen, then type

% grep science science.txt

As you can see, grep has printed out each line containg the word science.

Or has it ????

Try typing

% grep Science science.txt

The grep command is case sensitive; it distinguishes between Science and science.

To ignore upper/lower case distinctions, use the -i option, i.e. type

% grep -i science science.txt

To search for a phrase or pattern, you must enclose it in single quotes (the apostrophe symbol). For example to search for spinning top, type

% grep -i 'spinning top' science.txt

Some of the other options of grep are:

-v display those lines that do NOT match
-n precede each matching line with the line number
-c print only the total count of matched lines

Try some of them and see the different results. Don't forget, you can use more than one option at a time. For example, the number of lines without the words science or Science is

% grep -ivc science science.txt

wc (word count)

A handy little utility is the wc command, short for word count. To do a word count on science.txt, type

% wc -w science.txt

To find out how many lines the file has, type

% wc -l science.txt


Command Meaning
cp file1 file2 copy file1 and call it file2
mv file1 file2 move or rename file1 to file2
rm file remove a file
rmdir directory remove a directory
cat file display a file
less file display a file a page at a time
head file display the first few lines of a file
tail file display the last few lines of a file
grep 'keyword' file search a file for keywords
wc file count number of lines/words/characters in file

UNIX Chapter 3

3.1 Redirection

Most processes initiated by UNIX commands write to the standard output (that is, they write to the terminal screen), and many take their input from the standard input (that is, they read it from the keyboard). There is also the standard error, where processes write their error messages, by default, to the terminal screen.

We have already seen one use of the cat command to write the contents of a file to the screen.

Now type cat without specifing a file to read

% cat

Then type a few words on the keyboard and press the [Return] key.

Finally hold the [Ctrl] key down and press [d] (written as ^D for short) to end the input.

What has happened?

If you run the cat command without specifing a file to read, it reads the standard input (the keyboard), and on receiving the 'end of file' (^D), copies it to the standard output (the screen).

In UNIX, we can redirect both the input and the output of commands.

3.2 Redirecting the Output

We use the > symbol to redirect the output of a command. For example, to create a file called list1 containing a list of fruit, type

% cat > list1

Then type in the names of some fruit. Press [Return] after each one.

^D {this means press [Ctrl] and [d] to stop}

What happens is the cat command reads the standard input (the keyboard) and the > redirects the output, which normally goes to the screen, into a file called list1

To read the contents of the file, type

% cat list1

Exercise 3a

Using the above method, create another file called list2 containing the following fruit: orange, plum, mango, grapefruit. Read the contents of list2

3.2.1 Appending to a file

The form >> appends standard output to a file. So to add more items to the file list1, type

% cat >> list1

Then type in the names of more fruit

^D (Control D to stop)

To read the contents of the file, type

% cat list1

You should now have two files. One contains six fruit, the other contains four fruit.

We will now use the cat command to join (concatenate) list1 and list2 into a new file called biglist. Type

% cat list1 list2 > biglist

What this is doing is reading the contents of list1 and list2 in turn, then outputing the text to the file biglist

To read the contents of the new file, type

% cat biglist

3.3 Redirecting the Input

We use the <>

The command sort alphabetically or numerically sorts a list. Type

% sort

Then type in the names of some animals. Press [Return] after each one.

^D (control d to stop)

The output will be


Using <>

% sort <>

and the sorted list will be output to the screen.

To output the sorted list to a file, type,

% sort <> slist

Use cat to read the contents of the file slist

3.4 Pipes

To see who is on the system with you, type

% who

One method to get a sorted list of names is to type,

% who > names.txt

% sort <>

This is a bit slow and you have to remember to remove the temporary file called names when you have finished. What you really want to do is connect the output of the who command directly to the input of the sort command. This is exactly what pipes do. The symbol for a pipe is the vertical bar |

For example, typing

% who | sort

will give the same result as above, but quicker and cleaner.

To find out how many users are logged on, type

% who | wc -l

Exercise 3b

Using pipes, display all lines of list1 and list2 containing the letter 'p', and sort the result.

Answer available here


Command Meaning
command > file redirect standard output to a file
command >> file append standard output to a file
command < file redirect standard input from a file
command1 | command2 pipe the output of command1 to the input of command2
cat file1 file2 > file0 concatenate file1 and file2 to file0
sort sort data
who list users currently logged in

UNIX Chapter 4

4.1 Wildcards

The * wildcard

The character * is called a wildcard, and will match against none or more character(s) in a file (or directory) name. For example, in your unixstuff directory, type

% ls list*

This will list all files in the current directory starting with list....

Try typing

% ls *list

This will list all files in the current directory ending with ....list

The ? wildcard

The character ? will match exactly one character.
So ?ouse will match files like house and mouse, but not grouse.
Try typing

% ls ?list

4.2 Filename conventions

We should note here that a directory is merely a special type of file. So the rules and conventions for naming files apply also to directories.

In naming files, characters with special meanings such as / * & % , should be avoided. Also, avoid using spaces within names. The safest way to name a file is to use only alphanumeric characters, that is, letters and numbers, together with _ (underscore) and . (dot).

Good filenames Bad filenames
project.txt project
my_big_program.c my big program.c
fred_dave.doc fred & dave.doc

File names conventionally start with a lower-case letter, and may end with a dot followed by a group of letters indicating the contents of the file. For example, all files consisting of C code may be named with the ending .c, for example, prog1.c . Then in order to list all files containing C code in your home directory, you need only type ls *.c in that directory.

4.3 Getting Help

On-line Manuals

There are on-line manuals which gives information about most commands. The manual pages tell you which options a particular command can take, and how each option modifies the behaviour of the command. Type man command to read the manual page for a particular command.

For example, to find out more about the wc (word count) command, type

% man wc


% whatis wc

gives a one-line description of the command, but omits any information about options etc.


When you are not sure of the exact name of a command,

% apropos keyword

will give you the commands with keyword in their manual page header. For example, try typing

% apropos copy


Command Meaning
* match any number of characters
? match one character
man command read the online manual page for a command
whatis command brief description of a command
apropos keyword match commands with keyword in their man pages

UNIX Chapter 5

5.1 File system security (access rights)

In your unixstuff directory, type

% ls -l (l for long listing!)

You will see that you now get lots of details about the contents of your directory, similar to the example below.

File and directory access rights

Each file (and directory) has associated access rights, which may be found by typing ls -l. Also, ls -lg gives additional information as to which group owns the file (beng95 in the following example):

-rwxrw-r-- 1 ee51ab beng95 2450 Sept29 11:52 file1

In the left-hand column is a 10 symbol string consisting of the symbols d, r, w, x, -, and, occasionally, s or S. If d is present, it will be at the left hand end of the string, and indicates a directory: otherwise - will be the starting symbol of the string.

The 9 remaining symbols indicate the permissions, or access rights, and are taken as three groups of 3.

  • The left group of 3 gives the file permissions for the user that owns the file (or directory) (ee51ab in the above example);
  • the middle group gives the permissions for the group of people to whom the file (or directory) belongs (eebeng95 in the above example);
  • the rightmost group gives the permissions for all others.

The symbols r, w, etc., have slightly different meanings depending on whether they refer to a simple file or to a directory.

Access rights on files.

  • r (or -), indicates read permission (or otherwise), that is, the presence or absence of permission to read and copy the file
  • w (or -), indicates write permission (or otherwise), that is, the permission (or otherwise) to change a file
  • x (or -), indicates execution permission (or otherwise), that is, the permission to execute a file, where appropriate

Access rights on directories.

  • r allows users to list files in the directory;
  • w means that users may delete files from the directory or move files into it;
  • x means the right to access files in the directory. This implies that you may read files in the directory provided you have read permission on the individual files.

So, in order to read a file, you must have execute permission on the directory containing that file, and hence on any directory containing that directory as a subdirectory, and so on, up the tree.

Some examples

-rwxrwxrwx a file that everyone can read, write and execute (and delete).
-rw------- a file that only the owner can read and write - no-one else
can read or write and no-one has execution rights (e.g. your
mailbox file).

5.2 Changing access rights

chmod (changing a file mode)

Only the owner of a file can use chmod to change the permissions of a file. The options of chmod are as follows

Symbol Meaning
u user
g group
o other
a all
r read
w write (and delete)
x execute (and access directory)
+ add permission
- take away permission

For example, to remove read write and execute permissions on the file biglist for the group and others, type

% chmod go-rwx biglist

This will leave the other permissions unaffected.

To give read and write permissions on the file biglist to all,

% chmod a+rw biglist

Exercise 5a

Try changing access permissions on the file science.txt and on the directory backups

Use ls -l to check that the permissions have changed.

5.3 Processes and Jobs

A process is an executing program identified by a unique PID (process identifier). To see information about your processes, with their associated PID and status, type

% ps

A process may be in the foreground, in the background, or be suspended. In general the shell does not return the UNIX prompt until the current process has finished executing.

Some processes take a long time to run and hold up the terminal. Backgrounding a long process has the effect that the UNIX prompt is returned immediately, and other tasks can be carried out while the original process continues executing.

Running background processes

To background a process, type an & at the end of the command line. For example, the command sleep waits a given number of seconds before continuing. Type

% sleep 10

This will wait 10 seconds before returning the command prompt %. Until the command prompt is returned, you can do nothing except wait.

To run sleep in the background, type

% sleep 10 &

[1] 6259

The & runs the job in the background and returns the prompt straight away, allowing you do run other programs while waiting for that one to finish.

The first line in the above example is typed in by the user; the next line, indicating job number and PID, is returned by the machine. The user is be notified of a job number (numbered from 1) enclosed in square brackets, together with a PID and is notified when a background process is finished. Backgrounding is useful for jobs which will take a long time to complete.

Backgrounding a current foreground process

At the prompt, type

% sleep 1000

You can suspend the process running in the foreground by typing ^Z, i.e.hold down the [Ctrl] key and type [z]. Then to put it in the background, type

% bg

Note: do not background programs that require user interaction e.g. vi

5.4 Listing suspended and background processes

When a process is running, backgrounded or suspended, it will be entered onto a list along with a job number. To examine this list, type

% jobs

An example of a job list could be

[1] Suspended sleep 1000
[2] Running netscape
[3] Running matlab

To restart (foreground) a suspended processes, type

% fg %jobnumber

For example, to restart sleep 1000, type

% fg %1

Typing fg with no job number foregrounds the last suspended process.

5.5 Killing a process

kill (terminate or signal a process)

It is sometimes necessary to kill a process (for example, when an executing program is in an infinite loop)

To kill a job running in the foreground, type ^C (control c). For example, run

% sleep 100

To kill a suspended or background process, type

% kill %jobnumber

For example, run

% sleep 100 &
% jobs

If it is job number 4, type

% kill %4

To check whether this has worked, examine the job list again to see if the process has been removed.

ps (process status)

Alternatively, processes can be killed by finding their process numbers (PIDs) and using kill PID_number

% sleep 1000 &
% ps

20077 pts/5 S 0:05 sleep 1000
21563 pts/5 T 0:00 netscape
21873 pts/5 S 0:25 nedit

To kill off the process sleep 1000, type

% kill 20077

and then type ps again to see if it has been removed from the list.

If a process refuses to be killed, uses the -9 option, i.e. type

% kill -9 20077

Note: It is not possible to kill off other users' processes !!!


Command Meaning
ls -lag list access rights for all files
chmod [options] file change access rights for named file
command & run command in background
^C kill the job running in the foreground
^Z suspend the job running in the foreground
bg background the suspended job
jobs list current jobs
fg %1 foreground job number 1
kill %1 kill job number 1
ps list current processes
kill 26152 kill process number 26152

UNIX Chapter 6

Other useful UNIX commands


All students are allocated a certain amount of disk space on the file system for their personal files, usually about 100Mb. If you go over your quota, you are given 7 days to remove excess files.

To check your current quota and how much of it you have used, type

% quota -v


The df command reports on the space left on the file system. For example, to find out how much space is left on the fileserver, type

% df .


The du command outputs the number of kilobyes used by each subdirectory. Useful if you have gone over quota and you want to find out which directory has the most files. In your home-directory, type

% du -s *

The -s flag will display only a summary (total size) and the * means all files and directories.


This reduces the size of a file, thus freeing valuable disk space. For example, type

% ls -l science.txt

and note the size of the file using ls -l . Then to compress science.txt, type

% gzip science.txt

This will compress the file and place it in a file called science.txt.gz

To see the change in size, type ls -l again.

To expand the file, use the gunzip command.

% gunzip science.txt.gz


zcat will read gzipped files without needing to uncompress them first.

% zcat science.txt.gz

If the text scrolls too fast for you, pipe the output though less .

% zcat science.txt.gz | less


file classifies the named files according to the type of data they contain, for example ascii (text), pictures, compressed data, etc.. To report on all files in your home directory, type

% file *


This command compares the contents of two files and displays the differences. Suppose you have a file called file1 and you edit some part of it and save it as file2. To see the differences type

% diff file1 file2

Lines beginning with a < denotes file1, while lines beginning with a > denotes file2.


This searches through the directories for files and directories with a given name, date, size, or any other attribute you care to specify. It is a simple command but with many options - you can read the manual by typing man find.

To search for all fies with the extention .txt, starting at the current directory (.) and working through all sub-directories, then printing the name of the file to the screen, type

% find . -name "*.txt" -print

To find files over 1Mb in size, and display the result as a long listing, type

% find . -size +1M -ls


The C shell keeps an ordered list of all the commands that you have entered. Each command is given a number according to the order it was entered.

% history (show command history list)

If you are using the C shell, you can use the exclamation character (!) to recall commands easily.

% !! (recall last command)

% !-3 (recall third most recent command)

% !5 (recall 5th command in list)

% !grep (recall last command starting with grep)

You can increase the size of the history buffer by typing

% set history=100

UNIX Chapter 7

7.1 Compiling UNIX software packages

We have many public domain and commercial software packages installed on our systems, which are available to all users. However, students are allowed to download and install small software packages in their own home directory, software usually only useful to them personally.

There are a number of steps needed to install the software.

  • Locate and download the source code (which is usually compressed)
  • Unpack the source code
  • Compile the code
  • Install the resulting executable
  • Set paths to the installation directory

Of the above steps, probably the most difficult is the compilation stage.

Compiling Source Code

All high-level language code must be converted into a form the computer understands. For example, C language source code is converted into a lower-level language called assembly language. The assembly language code made by the previous stage is then converted into object code which are fragments of code which the computer understands directly. The final stage in compiling a program involves linking the object code to code libraries which contain certain built-in functions. This final stage produces an executable program.

To do all these steps by hand is complicated and beyond the capability of the ordinary user. A number of utilities and tools have been developed for programmers and end-users to simplify these steps.

make and the Makefile

The make command allows programmers to manage large programs or groups of programs. It aids in developing large programs by keeping track of which portions of the entire program have been changed, compiling only those parts of the program which have changed since the last compile.

The make program gets its set of compile rules from a text file called Makefile which resides in the same directory as the source files. It contains information on how to compile the software, e.g. the optimisation level, whether to include debugging info in the executable. It also contains information on where to install the finished compiled binaries (executables), manual pages, data files, dependent library files, configuration files, etc.

Some packages require you to edit the Makefile by hand to set the final installation directory and any other parameters. However, many packages are now being distributed with the GNU configure utility.


As the number of UNIX variants increased, it became harder to write programs which could run on all variants. Developers frequently did not have access to every system, and the characteristics of some systems changed from version to version. The GNU configure and build system simplifies the building of programs distributed as source code. All programs are built using a simple, standardised, two step process. The program builder need not install any special tools in order to build the program.

The configure shell script attempts to guess correct values for various system-dependent variables used during compilation. It uses those values to create a Makefile in each directory of the package.

The simplest way to compile a package is:

  1. cd to the directory containing the package's source code.
  2. Type ./configure to configure the package for your system.
  3. Type make to compile the package.
  4. Optionally, type make check to run any self-tests that come with the package.
  5. Type make install to install the programs and any data files and documentation.
  6. Optionally, type make clean to remove the program binaries and object files from the source code directory

The configure utility supports a wide variety of options. You can usually use the --help option to get a list of interesting options for a particular configure script.

The only generic options you are likely to use are the --prefix and --exec-prefix options. These options are used to specify the installation directories.

The directory named by the --prefix option will hold machine independent files such as documentation, data and configuration files.

The directory named by the --exec-prefix option, (which is normally a subdirectory of the --prefix directory), will hold machine dependent files such as executables.

7.2 Downloading source code

For this example, we will download a piece of free software that converts between different units of measurements.

First create a download directory

% mkdir download

Download the software here and save it to your new download directory.

7.3 Extracting the source code

Go into your download directory and list the contents.

% cd download
% ls -l

As you can see, the filename ends in tar.gz. The tar command turns several files and directories into one single tar file. This is then compressed using the gzip command (to create a tar.gz file).

First unzip the file using the gunzip command. This will create a .tar file.

% gunzip units-1.74.tar.gz

Then extract the contents of the tar file.

% tar -xvf units-1.74.tar

Again, list the contents of the download directory, then go to the units-1.74 sub-directory.

% cd units-1.74

7.4 Configuring and creating the Makefile

The first thing to do is carefully read the README and INSTALL text files (use the less command). These contain important information on how to compile and run the software.

The units package uses the GNU configure system to compile the source code. We will need to specify the installation directory, since the default will be the main system area which you will not have write permissions for. We need to create an install directory in your home directory.

% mkdir ~/units174

Then run the configure utility setting the installation path to this.

% ./configure --prefix=$HOME/units174

NOTE: The $HOME variable is an example of an environment variable. The value of $HOME is the path to your home directory. Just type

% echo $HOME

to show the contents of this variable. We will learn more about environment variables in a later chapter.

If configure has run correctly, it will have created a Makefile with all necessary options. You can view the Makefile if you wish (use the less command), but do not edit the contents of this.

7.5 Building the package

Now you can go ahead and build the package by running the make command.

% make

After a minute or two (depending on the speed of the computer), the executables will be created. You can check to see everything compiled successfully by typing

% make check

If everything is okay, you can now install the package.

% make install

This will install the files into the ~/units174 directory you created earlier.

7.6 Running the software

You are now ready to run the software (assuming everything worked).

% cd ~/units174

If you list the contents of the units directory, you will see a number of subdirectories.

bin The binary executables
info GNU info formatted documentation
man Man pages
share Shared data files

To run the program, change to the bin directory and type

% ./units

As an example, convert 6 feet to metres.

You have: 6 feet
You want: metres

* 1.8288

If you get the answer 1.8288, congratulations, it worked.

To view what units it can convert between, view the data file in the share directory (the list is quite comprehensive).

To read the full documentation, change into the info directory and type

% info

7.7 Stripping unnecessary code

When a piece of software is being developed, it is useful for the programmer to include debugging information into the resulting executable. This way, if there are problems encountered when running the executable, the programmer can load the executable into a debugging software package and track down any software bugs.

This is useful for the programmer, but unnecessary for the user. We can assume that the package, once finished and available for download has already been tested and debugged. However, when we compiled the software above, debugging information was still compiled into the final executable. Since it is unlikey that we are going to need this debugging information, we can strip it out of the final executable. One of the advantages of this is a much smaller executable, which should run slightly faster.

What we are going to do is look at the before and after size of the binary file. First change into the bin directory of the units installation directory.

% cd ~/units174/bin
% ls -l

As you can see, the file is over 100 kbytes in size. You can get more information on the type of file by using the file command.

% file units

units: ELF 32-bit LSB executable, Intel 80386, version 1, dynamically linked (uses shared libs), not stripped

To strip all the debug and line numbering information out of the binary file, use the strip command

% strip units
% ls -l

As you can see, the file is now 36 kbytes - a third of its original size. Two thirds of the binary file was debug code!!!

Check the file information again.

% file units

units: ELF 32-bit LSB executable, Intel 80386, version 1, dynamically linked (uses shared libs), stripped

Sometimes you can use the make command to install pre-stripped copies of all the binary files when you install the package. Instead of typing make install, simply type make install-strip

UNIX Chapter 8

8.1 UNIX Variables

Variables are a way of passing information from the shell to programs when you run them. Programs look "in the environment" for particular variables and if they are found will use the values stored. Some are set by the system, others by you, yet others by the shell, or any program that loads another program.

Standard UNIX variables are split into two categories, environment variables and shell variables. In broad terms, shell variables apply only to the current instance of the shell and are used to set short-term working conditions; environment variables have a farther reaching significance, and those set at login are valid for the duration of the session. By convention, environment variables have UPPER CASE and shell variables have lower case names.

8.2 Environment Variables

An example of an environment variable is the OSTYPE variable. The value of this is the current operating system you are using. Type

% echo $OSTYPE

More examples of environment variables are

  • USER (your login name)
  • HOME (the path name of your home directory)
  • HOST (the name of the computer you are using)
  • ARCH (the architecture of the computers processor)
  • DISPLAY (the name of the computer screen to display X windows)
  • PRINTER (the default printer to send print jobs)
  • PATH (the directories the shell should search to find a command)

Finding out the current values of these variables.

ENVIRONMENT variables are set using the setenv command, displayed using the printenv or env commands, and unset using the unsetenv command.

To show all values of these variables, type

% printenv | less

8.3 Shell Variables

An example of a shell variable is the history variable. The value of this is how many shell commands to save, allow the user to scroll back through all the commands they have previously entered. Type

% echo $history

More examples of shell variables are

  • cwd (your current working directory)
  • home (the path name of your home directory)
  • path (the directories the shell should search to find a command)
  • prompt (the text string used to prompt for interactive commands shell your login shell)

Finding out the current values of these variables.

SHELL variables are both set and displayed using the set command. They can be unset by using the unset command.

To show all values of these variables, type

% set | less

So what is the difference between PATH and path ?

In general, environment and shell variables that have the same name (apart from the case) are distinct and independent, except for possibly having the same initial values. There are, however, exceptions.

Each time the shell variables home, user and term are changed, the corresponding environment variables HOME, USER and TERM receive the same values. However, altering the environment variables has no effect on the corresponding shell variables.

PATH and path specify directories to search for commands and programs. Both variables always represent the same directory list, and altering either automatically causes the other to be changed.

8.4 Using and setting variables

Each time you login to a UNIX host, the system looks in your home directory for initialisation files. Information in these files is used to set up your working environment. The C and TC shells uses two files called .login and .cshrc (note that both file names begin with a dot).

At login the C shell first reads .cshrc followed by .login

.login is to set conditions which will apply to the whole session and to perform actions that are relevant only at login.

.cshrc is used to set conditions and perform actions specific to the shell and to each invocation of it.

The guidelines are to set ENVIRONMENT variables in the .login file and SHELL variables in the .cshrc file.

WARNING: NEVER put commands that run graphical displays (e.g. a web browser) in your .cshrc or .login file.

8.5 Setting shell variables in the .cshrc file

For example, to change the number of shell commands saved in the history list, you need to set the shell variable history. It is set to 100 by default, but you can increase this if you wish.

% set history = 200

Check this has worked by typing

% echo $history

However, this has only set the variable for the lifetime of the current shell. If you open a new xterm window, it will only have the default history value set. To PERMANENTLY set the value of history, you will need to add the set command to the .cshrc file.

First open the .cshrc file in a text editor. An easy, user-friendly editor to use is nedit.

% nedit ~/.cshrc

Add the following line AFTER the list of other commands.

set history = 200

Save the file and force the shell to reread its .cshrc file buy using the shell source command.

% source .cshrc

Check this has worked by typing

% echo $history

8.6 Setting the path

When you type a command, your path (or PATH) variable defines in which directories the shell will look to find the command you typed. If the system returns a message saying "command: Command not found", this indicates that either the command doesn't exist at all on the system or it is simply not in your path.

For example, to run units, you either need to directly specify the units path (~/units174/bin/units), or you need to have the directory ~/units174/bin in your path.

You can add it to the end of your existing path (the $path represents this) by issuing the command:

% set path = ($path ~/units174/bin)

Test that this worked by trying to run units in any directory other that where units is actually located.

% cd
% units

To add this path PERMANENTLY, add the following line to your .cshrc AFTER the list of other commands.

set path = ($path ~/units174/bin)

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