TK's FWA

[tk-fwa]

Installing applications on Linux with apt-get

This post answers these questions:

How do I install on Ubuntu/Linux Mint/Bodhi/(a Linux based off Debian) on the command line?

How do I use apt-get?

When should I use apt-get update?

What is the build-essential package for?

I used "apt-get install <package>" as instructed. Why does my package not install cleanly?

There are several ways to install applications on Linux, depending on your distribution, but for the purpose of this particular article, I am going to focus on the Debian family, which use the apt-get utility - this includes the more popular distributions, Ubuntu and Linux Mint. The distro I use in my VMs at the moment is Bodhi, a lightweight distribution, requiring very little memory, disk space, and CPU speed.

One way to install applications is to use the application manager, but try to not use that. If you've decided to launch yourself into Linux, you should familiarize yourself with installing from the command line using the apt-get utility, as a number of programs you'll come across may require it.

APT and repositories

APT, the Advanced Packaging Tool, is a utility that helps you install applications from one or more repositories. In the most simplistic terms, the repositories are online servers that host numerous versions of a vast number of applications, and the package manager is the utility that connects to these repositories, and installs apps, also known as packages. Depending on the Linux distribution, the corresponding repository may systematically make the latest versions of applications available, or only the latest known stable and fully tested version.

For example, Fedora tends to have the most up to date applications; the repository servers are maintained by Red Hat (who make Fedora) who make these latest versions available through their servers.

The Ubuntu family however is known to be less so keen on such practices, and only publish certain versions, known to play well with their OS. Canonical maintain the servers that Ubuntu uses.

Other offshoot distributions may also use another distro's repository so long as they are compatible. Thus Bodhi, which is based on Ubuntu, uses Canonical's repository.

You may think this is hardly more than an App Store for Linux, but there's a more technical side to it - these repositories do not only hold applications, but libraries, code packages that other applications can use. Windows users are perhaps more familiar with the "missing DLL" errors, Mac users probably know they need to hunt for other apps to support the app they are trying to run.

Linux packages however also come with a list of packages they depend on. The package manager on your computer then figures out what it needs to install first, what versions and in what order, before installing the package you told it to install. It will make sure another program that uses a different version of the package doesn't mess with your first app; and when you come to uninstalling the package, it will also remove any packages that are no longer necessary in your system.

And that's very neat.

Commands

In the following text, command prompts are indicated by starting with "$>" - so if a command is listed as   $> apt-get update this means to use the terminal program and run the command "apt-get update"

About sudo

You will find most commands in this article start with the word "sudo".

sudo (pronounced "soo-doo" by purists, I say it "soo-doh" like "pseudo") is a special command, which means "run the following command with root privilege." Most of the time, you are best not running any commands as root - this is a failsafe to prevent you from doing something silly, like deleting your entire system. Which, yes, you can end up doing if you're not careful. sudo tells the machine you really mean it. Before it does anything, it will ask you for either the system root password, or, if you have admin rights, your password. If you run a second sudo command soon after, it may not ask you again, depending on distro.

And so, without further ado, we come to the installation incantations!

Preparation

Before you do any installation, you will need to make sure that the apt-get utility is aware of all the latest versions, and crucially, dependencies.

  $> sudo apt-get update This will update APT's dependency library, as well as updating the URLs to various package repositories to the most recent. This is a very important step, and a command you should (read: must) run before a session of installing and un-installing packages.

The very first time you're installing software, you might want to run the following command:   $> sudo apt-get install build-essential This will install a number of other packages that are generally required to build applications from source, most notably the GNU C and C++ compiler suites and libraries. "./make" files, installer scripts which usually ship with source code downloaded from the web, generally depend on this.

Installing

The basic command for installing a package is   $> sudo apt-get install <package> where you replace "<package>" with the name of what you want to install. For example   $> sudo apt-get install abiword to install the AbiWord package. To install a specific version of a package, specify it after an equals sign, for example   $> sudo apt-get install abiword=2.4.6

You will be asked whether to proceed, after having been given a summary of what packages will be updated and how much extra space will eventually be taken on your system.

Session

In order of operation then:

On a new Linux, run: $> sudo apt-get update $> sudo apt-get install build-essential

When installing an application for the first time in the day, run apt-get update first, then start installing using apt-get install <package>.

Building from source code

If you download the source code for a package from off the web, you'll normally be given a README and a 'make' file. The Makefile as it is called contains instructions for building in various modes. Most often, simply switching to the directory and running the following will work (but please, do always read the README file first - do it the courtesy of its name!)   $> sudo apt-get update   $> sudo apt-get build-essential   $> sudo ./make install

This also holds true if you're given an installer file - for example, the VirtualBox Guest Additions has a script for installing the VirtualBox add-ons, which requires the build-essential package to be installed. It doesn't tell you so though - instead, it advises that it couldn't find gcc (the C compiler).

Updating your OS

From your old Windows or Mac OS X habit, you might be tempted to upgrade from one version of your Linux distro to the newest when it comes along. The general advice across the community is: don't. Not unless you are running an experimental system you don't mind losing.

From the Linux Mint upgrade notes: "Unless you need to, or unless you really want to, there's no reason for you to upgrade." This is an important concept of Linux distributions in general.

Linux versions come with newer interfaces, might add new file system support, and various other features - but rarely anything so ground-breaking that you'd be left behind if you didn't update.

For more on the topic, check the Linux Mint Community pages on the topic.

Conclusion

That's the end of the tutorial. Have fun installing lots of fun apps - take a look at this list for a start, and happy installing!

[tk-fwa]

How to move a dialog you can't see (Windows)

This post answers issues like:

I cannot see my window

Why did my window draw off screen?

How do I get my window back onto my screen?

My window still draws on a monitor that does not exist

How do I move a window I can't see?

Why does my window draw off screen?

Every office I've been at I've had the chance to wield two screens. It's really helpful when you're trying to handle many windows at once.

Something that plagues users such as I though is that any time you make a change to your screen setup, you risk falling into the trap of the off-screen window.

off screen window : a generic window can be maximized, and you see it has a preence in the task bar along with all your other windows.

off screen dialog : a dialog is the type of window that tells/asks you something with buttons such as "OK", "Cancel" etc. or perform a task such as display the search fields for your program. This does not appear in the task bar, and the only way you know it exists is that your otherwise current window is dimmed.

Either way, the ideal course of action would be to get it back. But how? Your mouse can't reach it.

Thanks to this blog post by Seraph3D, I found that we can do the following:

Do whatever action makes the dialog/window activate. Do not touch your mouse once this is done.

Press Alt+Spacebar

You should see a drop down menu appear somewhere. Select the "Move option". If you don't, then, if it's a regular window, press the Down key on your keyboard then enter; if it's a dialog just press enter.

Still without having moved the mouse, hit the Left arrow key on your keyboard. This makes the window locked to your mouse. Wherever the mouse moves to, the window will now follow!

Click your mouse to undo the lock and get your mouse back.

What a relief!

EDIT: One situation in which the above instructions do not work is when using a virtual machine window such as that of VirtualBox. The steps instead are as follows:

hover over the taskbar button for VirtualBox - you will see the Aero peek and the window you want to grab

right-click the window's aero thumbnail and select to maximize

the window should now be full screen, but still displaying the title bar - drag this

I believe that this works also for other regular windows. For the dialogs... the first method is still the only way.

[tk-fwa]

Ideal staffing levels for support teams

Prompted by a question on another site, I decided to do a little reasoning and napkin calculations to provide an answer based on my own experience. Note that whilst the below is an mainly an exercise in reasoning, and still needs work, I am fairly confident it is relevant to real world application.

Extended reasoning on staffing level calculation:

Let T be the time in hours it takes 1 person to clear an issue (in the real world, you would get this by finding the median duration of a support case)

Let I be the inbound volume of incidents over a period P (sample this from analyzing your own operations)

(thus, let P be a sample time period in days as a representative basis for T and I)

Let D be the number of hours any one given person is expected to work in a day (not including lunch time allowance)

Let H be the number of staff in the team (this is the number we are looking for)

Let W be the total number of work hours in period P, that being calculated as: W=H*D*P

When operating an issue-based service team, ideally you should see that over a period of time, your total case load should not have grown. If it increases you are understaffed; if it decreases dramatically you are overstaffed (allow however for transition into busy and lull periods).

The throughput (number of cases per period P) of the team then is W/T: as many cases taking T hours to solve should fit into W hours of work.

If over the same period of time, the same number of items came in (your inbound volume I) as "went out" (issues resolved), you are at balance. Thus, you want I to be equal to, or slightly smaller, than your throughput: I <= W/T

Now comes the interesting part. From the definition of W, we can substitute:

I <= H*D*P/T

Since we are looking for H, we isolate it, as follows:

H >= (I*T)/(D*P)

This is your formula for the ideal staffing level.

Example 1:

Consider a 1st line operation with numbers thus:

I = 120*5 T = 0.5 P = 5 D = 8

Applying the relation we get H = 300/40 = 7.5

So probably 8 people for 120 calls per day over a week.

Example 2:

Consider a 2nd line operation with numbers thus:

I = 15 T = 20 P = 5 (one working week) D = 8

Applying the relation we get H = 300/40 = 7.5

A team operating thus would need about 7 people in it, probably 8 to cater for peak times, sick times and time taken up by very difficult or large issues.

[versefoodtech]

Colour Spaces mini-Demo

Prompted by a question from a friend, I did a brief read-up on colour spaces, as the concept still eluded me somewhat. One very useful entry I found was at HiDefColor.com What I found was very interesting:

In a nutshell, a colour space defines the collection and limit of the total set of colours that can be represented in that space. The RGB colour space due to it being additive, can represent more vibrant colours than CMYK space.

As a mini-demo, I provide above one of my photos:

rendered in using AdobeRGB space (top left)

converted to, and rendered in, Generic CMYK space (bottom left)

and the same CMYK after having maxed out the Contrast properties

It speaks for itself.

All this time I thought vibrant photos on screen would turn out vibrant in print. Nope. Converting to a CMYK colourspace as the final stage in the workflow gives a preview of what will happen to those flashy colours when the image is printed. Thank goodness.

This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.

[tk-fwa]

From one of my other blogs.

Questions answered:

What are colourspaces?

What is the difference between CMYK and RGB colourspaces?

Why is my CMYK photo lower quality than its RGB equivalent?

Should I work in CMYK or RGB colourspace?

[versefoodtech]

Olympus Trip 35

[tk-fwa]

From one of my other blogs - some details about the Olympus Trip 35. I got these whilst scouring the web last year, but I didn’t keep note of the sources so… Citation Needed all around!

Questions answered:

What is the shutter speed of the Olympus Trip?

Why did my Olympus Trip not use the aperture I set?

How do I overexpose on an Olympus Trip?

How does the Olympus Trip 35 determine exposure?

The Trip is a little... particular. The following is what I gleaned from the internet some time ago trying to hunt down the technical details. There is no single document to back up my statements below, so take them prudently ;-)

The default exposure time on a Trip 35 is around 1/100s

When you set aperture to 'A' it will auto-expose using the selenium cells around the lens by varying the aperture for an overall even tone. You may already know that if it judges the picture to be too dark, it won't release the shutter. The inset picture is mostly dark, the auto-expose would not capture that.

To force the shutter to release, you need to use a "manual" aperture setting.

The manual setting of the aperture is not an imperative - it informs the camera that the maximum aperture you want to allow is what you have set. If it can achieve a balanced picture with a narrower aperture, say f8 instead of f5.6, then it will use the narrower f8.

If it reaches your maximum aperture and still is not satisfied that the picture is bright enough, it switches to a 1/40s exposure.

You can also insert ISO 400 film but set the camera to ASA 200 for example - in this case since the camera will automatically calibrate for a less sensitive film, the aperture will open up further than if you had set it to ASA 400 (to match your film). In "normal" lighting conditions, this means that with ISO 400 film and ASA 200 setting, your picture will be brighter.

For night-time street captures then, ISO 400 film with settings at ASA 400, f2.8 and exposure 1/40s should yield the right results. Certainly, I always buy ISO 400 film these days, as I nearly always have a want to take photos in low-light.

I hope that serves as a useful summary of the basic considerations for using a Trip 35. It's a good little camera, albeit a little heavy...

[tk-fwa]

AutoArchive in Outlook 2003

Some users were reaching their mailbox size quota and I needed to be able to advise them on using AutoArchive with Outlook 2003 (yes, I know, it's old). I drafted the following mail to fully explain what AutoArchive does, how to use it, and the corollary consequences of using it.

Questions answered:

What does AutoArchive do?

How do I use AutoArchive?

Where did my emails go?

AutoArchiving will remove files from the server thus freeing-up space, and save them to a local disk. Full details are as follows:

Setting up AutoArchive

In MS Outlook 2003, you can configure Auto-Archive in menu [ Tools: Options ]

Go to the "Other" tab

Under the Auto Archive section click the "AutoArchive..." button

Adjust the settings accordingly; choose to MOVE old items (to an archive.PST file) rather than delete them, and apply the settings to all folders once done.

For the "Move old items to" setting, please choose to save the PST to an external drive. You can find these in any computer store, or online:

USB sticks

External hard drives

Anything up from 16 GB will likely be useful for your backups in general.

Click OK on each of the windows to come out of there.

Manually performing an AutoArchive (first time, for example)

Go to menu [ File : Archive ... ]

Select "Archive all folders according to their AutoArchive settings"

Click OK

What this will do

AutoArchive REMOVES the emails from the server and places them in the PST file you specified.

You will be able to access old emails in Outlook under the Archive Folders, as long as the PST file is accessible.

If for some reason Outlook cannot later find the PST file (started Outlook without the USB drive available, or starting Outlook on a different computer), choose menu [ File : Open : Outlook Data File ] and locate the PST file

The consequence of this move is that:

if you were using Outlook from a different location, that version of Outlook will not see the AutoArchived emails until you choose to open the Outlook Data File/PST file (as just above)

if you use the Outlook Web Access site (through a web browser), you will not see the AutoArchived emails. The OWA site cannot access PST files.

to access the old emails in the PST file, you will need MS Outlook (full version, not Outlook Express)

There are some free programs that might be able to read PST files, though I cannot comment on their completeness for such as task having never used them myself.