Linux Format Newsletter -- #42, October 2008

M-Saunders — Fri Nov 21, 2008 11:54 am

Author: M-Saunders

Posted: Fri Nov 21, 2008 11:54 am

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LINUX FORMAT WEBSITE NEWSLETTER -- #42, OCTOBER 2008

www.linuxformat.co.uk

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CONTENTS

1. Welcome!

2. LXF 112 on sale

3. In the news...

4. This month on the forum

5. Special Newsletter feature

6. Coming up next issue

7. Receiving this Newsletter

8. Contact details

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1. Welcome!
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This month we have a special subscription offer for LXF Newsletter
readers. For those based in the UK we're offering 3 issues for £3,
and then you pay just £13.99 every three months. Given that the
magazine on the newsstand costs £6.49, that's a huge saving! So if
you've been umming-and-ahhing about getting a subscription, now is
the time.

For non-UK readers, you can save up to 43%:

European Union: £67.99
Rest of the world: £70.00

Given the state of the world economy, you can't afford to miss it.
Indeed, you should take out several subscriptions and stockpile them
in a bunker alongside food and water.

Here's the URL: www.myfavouritemagazines.co.uk/lxd/2008

Meanwhile, enjoy this month's Newsletter with our look at the latest
issue of LXF, roundups of the hottest news stories and forum
threads, and a special feature on GUIfying your shell scripts.
If you have any comments or suggestions, drop me a line!

Mike Saunders
Newsletter Editor
Mike.Saunders@futurenet.com

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2. LXF 112 on sale
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Linux Format issue 112 is now on sale, ready to get your creative
juices flowing. In our bumper cover feature we show you how to make
sweet music, edit a movie and put together your own website using
the power of Free Software. OOo, Open Movie Editor, Kompozer and
Ubuntu Studio team up to provide a media production powerhouse -- so
if you're in the mood for making something new, don't miss it!

Also, we show you how to switch distros without losing your settings
and personal data, and help you to sand-down some of the rougher
edges of KDE 4. On our DVD we have the complete release of CentOS
5.2, an industrial-strength distro for your desktop, workstation or
server, plus a USB key distro kit so you can take Linux on the move.

In our regular HotPicks section we trawl the internet for top new or
updated open source releases, and this month Nick has been making
sure his kids don't hog the PC all day...

# KChildlock 0.50.1 -- http://sourceforge.net/projects/kchildlock

Children. Bless them. If you have any, you will no doubt be
familiar how no child protection device seems to be sufficient.
They will happily laugh as they bypass whatever hideously
complicated plastic contraption you have placed on the fridge or
the drinks cabinet before pouring your favourite malt whiskey all
over the carpet. Or maybe that's just us.

One place you can get the better of them is on the computer
though. While obviously you need to train the next generation and
set them on the true path of Unix, apparently too much computer
use can be bad for them (I'm sure it never did any of us any
harm). KChildlock is a simple daemon/application that can bring
the semblence of power and control back to your life. Run as root
(or add the daemon as a service) and it allows access control for
up to three specific users.

The granularity of the control is not excessive, but detailed
enough. You can set a curfew time for each day by blocking off
certain times from computer use. There is also the possibility of
setting a maximum usage allowance per day, just to make sure their
eyes don't get square. Of course, this only controls timed access
to the computer. It has no features to control what kids actually
do on the computer - if they spend the alloted time working out
how to gain root access to your files, it's rather up to you to
take more draconian measures.

Setting the access privileges is as simple as running the client
program and choosing Configure from the three options available.
The client also gives you the option to start or stop the service
manually. As it is built on KDE 3 libraries, you shouldn't have
any trouble compiling or installing it on any reasonable distro.
And remember, KChildlock isn't just for kids - you can control any
users' access to the system. Hahah! Take that you whiskey-stealing
layabouts.

See the LXF website (http://www.linuxformat.co.uk) and click on the
right-hand issue pic for a full lowdown on 112's contents.

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3. In the news
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New releases ahoy in September...

# Mandriva 2009 released, snubs year 2008
http://www.linuxformat.co.uk/modules.php?op=modload&name=News&file=article&sid=750

Are you bored of the year 2008, what with the global economic woes
and rubbish weather (at least in England)? Convince yourself that
it's already 2009 with a minty-fresh new distro release. Mandriva
2009.0 includes KDE 4.1.2, kernel 2.6.27, a late release candidate
of OpenOffice.org 3.0, and top-notch netbook hardware support.
Download from here or snag a copy from the upcoming LXF113 DVD.

# The LXF Test: OpenOffice.org 3.0
http://www.linuxformat.co.uk/modules.php?op=modload&name=News&file=article&sid=751

After a lengthy development cycle, we have a shiny new version of
OpenOffice.org to play around with. But has it been worth the wait?
Neil Bothwick rolls up his sleeves and picks apart OOo 3.0's new
features, finding out whether it deserves a major version number
bump and finally sorts out the performance woes...

# It's... Linux kernel 2.6.27
http://www.linuxformat.co.uk/modules.php?op=modload&name=News&file=article&sid=742

Linux

Crank up your compiler -- kernel 2.6.27 has arrived, including (deep
breath): a new filesystem (UBIFS) optimized for "pure" flash-based
storage devices; the page-cache is now lockless; much improved
Direct I/O scalability and performance; delayed allocation for ext4;
multiqueue networking; an alternative hibernation implementation
based on kexec/kdump; data integrity support in the block layer for
devices that support it; a simple tracer called ftrace; and loads
more tech.

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4. This month on the forum
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As covered in the news above, Mandriva 2009 was released earlier
this month, and Sentient One gave it a shot. He found it to be an
excellent release, and was chuffed that nigh-on everything worked
out-the-box. AdamW of the Mandriva team chipped in with help, and
Rhakios provided some technical information on the installation. If
you've given this distro a go, join in the thread -- or wait for the
One version on LXF113's DVD. [1]

Everyone needs to eat, but those of us firmly settled in Geekdom
rarely find time to prepare elaborate dishes. So we started a geek
food recipes thread in which forumers could post their hastily-
concocted dishes for all to see (and use). Inevitably, a few posters
pointed out that all you need is a phone and a credit card, and
pizzas will come flying your way... [2]

[1] http://www.linuxformat.co.uk/index.php?name=PNphpBB2&file=viewtopic&t=8769

[2] http://www.linuxformat.co.uk/index.php?name=PNphpBB2&file=viewtopic&t=8738

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5. Special Newsletter feature
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USING DIALOG BOXES IN SCRIPTS

Using Bash you can create powerful command-line scripts to perform
all manner of jobs, but how do you give the user feedback? If he or
she is running your script in a shell prompt, you can spit out text
to the terminal window and all is well. But if the user is running
it from a GUI, eg a file manager, the command line text will never
appear.

Zenity provides the perfect solution. This small program lets you
pop up graphical dialog boxes to get information or display error
messages as your script progresses. You can incorporate it into your
Bash scripts to create basic GUI-driven programs, and it's very easy
to use. At a shell prompt, enter this:

zenity --info --text "Finished"

You'll see a dialog box containing the word "Finished". Here, the
--info option tells Zenity that we want to display a simple
information dialog, and the --text parameter passes the string that
we want to appear.

You can make the dialog box more serious with:

zenity --warning --text "Disaster"

Instead of a generic message box icon, you'll get a red triangle,
which stands out more. You can also use Zenity to get input from a
user -- save the following as test.sh:

answer=$(zenity --entry --text="Enter your name")
zenity --info --text "Hello $answer"

Run it with "sh test.sh". The first line here pops up a text entry
box with a prompt to enter your name. We store the results of this
into a variable called answer, which we'll refer to subsequently as
$answer. In the second line, we pop up a dialog box saying "Hello"
followed by the name that the user inputted before.

What if you want the user to select a file? You could do this by
asking them to input a full filename and path using the text entry
box above, but Zenity has a better solution (again, save and run
this as test.sh):

filename=$(zenity --file-selection)
zenity --info --text "You chose $filename"

If your script is doing a lot of background processing, you may want
to alert the user when it has completed. For desktops and window
managers that include a notification area, you can do this with:

zenity --notification --text="All actions completed"

Here, a small icon will appear in the user's notification area, and
when they hover the mouse over the icon, they'll see the text we
included.

So Zenity is a very useful and versatile tool for adding GUI touches
to shell scripts. It's capable of much more too, from calendars to
progress bars, so enter "man zenity" to read the manual page and
look through some more advanced examples.

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6. Coming up next issue
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Linux Format 113, on sale Thursday 13 October...

# Build your own distro -- Get Linux your way with our
hands-on guide

# Budget Linux PCs -- Find a bargain in our Roundup

# Reader round table -- A gaggle of geeks discuss the
future of our favourite OS

(Exact contents of future issues are subject to change. Our
crystal ball needs an upgrade.)

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7. Receiving this Newsletter
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If you've been forwarded this Newsletter from someone else, and want
to sign up for future issues, just follow the steps below. Each
month you'll receive a sparkling new LXF Newsletter straight in your
Inbox, and the 30-second sign-up process is even easier than
putting in a light bulb:

1. Go to the website forums and log in (or sign up first):
http://www.linuxformat.co.uk/forums/

2. At the top of the main forum page, click on 'Usergroups'

3. Join the 'Newsletter' group, and you're done!

If for some reason you no longer wish to receive this newsletter
(which'll make the internet scream) you can opt-out like this:

1. Log into the LXF site and go to the forums
2. Click Usergroups at the top of the page
3. Select Newsletter and then View information
4. Click Unsubscribe next to 'You are a member...'

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8. Contact details
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If you have any questions or suggestions, please send them to the
Newsletter Editor at the address below:

Newsletter Editor: Mike Saunders -- Mike.Saunders@futurenet.com

Letters for the magazine: lxf.letters@futurenet.com

LXF website: http://www.linuxformat.co.uk

Subscriptions: 0870 837 4722 (overseas +44 1858 438794)
Website subscription page: http://www.linuxformat.co.uk/subscribe/

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(C) 2008 Future Publishing Limited

Linux Format forums

Linux Format Newsletter -- #42, October 2008