LJ Archive


Extracting Pages from a PDF File

In response to Jon GrosJean's question regarding the impossibility of tearing out pages from a digital version of our favourite magazine [see the February 2013 issue's Letters section], here is a command line to extract pages from a PDF file. Let's say you would like to keep a record of Shawn Powers' excellent Current_Issue.tar.gz column, which is on pages 8 and 9 of February's issue:

pdftops dlj226.pdf - | psselect -p8-9 | 
 ↪ps2pdf14 - shawn_Feb2013_article.pdf


Patrick Wolf

That beats my photocopy-the-tablet method—just teasing! Thanks Patrick, that's perfect!—Ed.

Plex—No Need to Use Native App

I just found Plex myself the other day, and I understand why it is the Editors' Choice for February 2013 issue. It is a rather impressive piece of software.

One detail I'd like to point out, however, is that you don't necessarily need the Android native app to use the server.

The app probably will help overcome some network complexities when you're out and about, and because I haven't tried it myself, I can't really comment on it in itself. What kept me from installing it was the fact that it costs (not much, but a little) money.

The way I use Plex on my LAN is via the browser. I just use the Android/iOS device's Web browser to connect to http://my.plex.server:32400/web, and I can stream my media just fine, without the need for the app.

Just a tip for the more frugal of us.

Mattias Fransson

Mattias, you are correct, and I actually tried to get the Web feature to work outside my LAN, but had a rough time. I know the folks at Plex are offering a premium subscription that allows Web streaming from anywhere, but I haven't looked into it much. I did have luck streaming on a LAN though, and I should have mentioned it. Thanks for bringing it up!—Ed.

Reply to Joseph Ziehmer's “Discouraging” Letter

I read Joseph Ziehmer's “Discouraging” letter (published in the February 2013 issue) about Linux in education, and the subject really hit home. As the Supervisor of Technology for a public school district in New Jersey, I too was amazed to discover how hard it is to implement what seems like a “no-brainer” solution: a free, fully loaded operation system that allows us to use older hardware, otherwise not suitable for running Windows 7.

“There is truthfully nothing that gets done as far as bringing Linux to the classroom”—this is the essence of the letter and a valuable point that the Linux community as a whole should address if it wants to “play in the big boys' league” one day. As long as teachers and students feel that Linux is not “user-friendly”, that it is cumbersome to use in an Active Directory environment, that one has to jump through hoops in order to save a file in one's network home directory, I'm afraid Linux will remain the “mystery of the few”. I know that it has grown tremendously in the past years, but it still barely scratches the 2% user base (at least in the US), and I think that part of the blame lies with the Linux community itself. If Linux cannot get a foothold in the classroom, especially in the K–12 environment, where students can get comfortable with it, learn the OS and its applications and use it on a daily basis, it will not stand much of chance to gain acceptance later, in colleges and in the enterprise. Students are exposed to technologies that are simple and work—Windows and Mac. They care little about grand concepts like “software freedom”. As an IT professional, I am tasked with making sure that technology works, integrates with the core curriculum and allows faculty and students to teach and learn better.

Sadly, I cannot say that my experience with introducing Linux in our district has been a particularly successful one. I deployed a couple dozen computers running Mint and faced many obstacles—the most stringent one being the inability to integrate them easily within our AD network environment. Simple tasks, such as having a default desktop with mapped network shares where different students can log in, work on documents (using Libre Office) and successfully save them in their home folders proved to be an elusive goal or necessitated way too much effort on the part of 4th and 5th graders. We did not have much luck trying the same with Ubuntu. I invested effort and time researching for solutions, asking questions in forums, even e-mailing Linux Journal for support, all to no avail. A few months later, we've reverted back to Windows 7 and all is well.

Although I am a Windows and Mac professional, I am also a Linux (newbie) user and enthusiast, and I would like to expand its use in my district because I believe that it is a valuable tool for education and can help broaden students' horizons. But I too was discouraged, disappointed by the experience and eventually, capitulated. It is one thing to use Linux on your personal computer, and it is quite another to use it in an enterprise environment, where it has to integrate with the existing infrastructure and confer the same user experience that a Windows or Mac does. Otherwise, Linux will continue to make huge gains and barely scratch the 3% user base.

Lucian Micu

I've not had too much experience integrating into an AD environment. I was lucky in that my Linux servers were at the core, and Windows/Mac clients were only workstations. In that scenario, my Linux workstations actually were the most convenient at file management thanks to NFS shares. It got a little more complex when I added an OS X server as the LDAP server for user authentication, but because I still had all Linux servers for file services, it worked fairly well.

I've spent most of my professional career implementing Linux solutions for K–12 schools, and I agree, it's often very very frustrating. If we ever meet at a conference, I'd love to have a conversation (or 12) about the topic. It's a passion I share with you.—Shawn Powers


To Shawn Powers: you mentioned (in the Upfront article on page 20 of the November 2009 issue) a SuperGamer Linux-only Gameplay DVD, but the site is not longer there. Do you have a new link for this DVD? (I have had my subscription only for a year, but I have downloaded all the back issues and am reading my way through them.)

Bob Dent

Sadly, the SuperGamer project has been discontinued. (I chalk it up with other bad ideas, like the cancellation of Firefly.)

The DVD is still available, I think, from DistroWatch. Here's the link to the information on SuperGamer: distrowatch.com/table.php?distribution=supergamer.

The silver lining is that Steam for Linux is more than just vaporware now, so there is hope for Linux gaming down that avenue!—Shawn Powers

Windows 8 UEFI and Linux

How about an article on the latest Microsoft block on Linux? We used to be able to run dual systems, but with the Windows 8 UEFI setup, it is virtually impossible. Even by enabling their Legacy, which disables UEFI, installing LM fails. My questions are: is Linux still working on this one, and are we going to be able to fight back with a solution in the near future? Thanks and keep up the good work.

By the way, all my machines are running on LinuxMint (I dumped Windows years ago), but I have friends that need dual systems, hence my request.

Riki Apperley

I recently read Linus' comment on the issue, and although I can't repeat it in the magazine, it certainly paints the picture for kernel support, LOL! There are some brilliant people working on user-space solutions, but with Microsoft being the only signing authority, it's an ugly situation.—Ed.


I may have this wrong, but one of the things that seems to be missing from Linux Journal is a report on what is happening with various Linux distributions, and what choices a user has. I have been a subscriber to Linux Journal for a number of years.

In the last couple days, I was completely blindside by a series of events. I am a long-term Mandriva user. I use CentOS for my local, home server to back up files. After I installed Windows 8 in a dual-boot system (I also had to install Ubuntu to get it all to work), I was having some problems with Mandriva. So, I signed into the Mandriva site to check on what was happening with upgrades and so forth. Low and behold, Mandriva no longer seemed to be supporting the desktop version. In a panic, I set up a test machine using an old HP Pentium 4 with a 2TB drive installed. Then I downloaded CentOS, Red Hat, SUSE, Ubuntu, Debian and Fedora—desktop versions just to start reviewing the various features and what I would have available as alternatives to Mandriva.

Today, I received an e-mail from Mandriva that announced a new server version, so I e-mailed back to ask if Mandriva was going to introduce a new desktop version. I learned that Mandriva is leaving the desktop business and will be serving the x64 server market. Then they pointed me toward another couple desktop distro sources, one at www.openmandriva.org and Mageia, upon which Mandriva's server is based is supposed to work as well for desktops (www.mageia.org).

The long and short of this is that as a reader, it would be helpful to me if you included a “Distro Column” that discussed what is going on in the industry, the pricing models and alternative distributions for desktops and servers. It also would be helpful to have a survey like the server survey to have readers report on their “desktop” versions, satisfaction and so on.

Steve Harris

We've done something similar on occasion in the past, and it's been a ton of fun. Although I'm sure we'll consider a regular distro-related section, at the very least I might steal your idea for my Open-Source Classroom column in a future issue. Thanks for the reminder, as it's certainly been a while since we've looked at distro comparisons.—Shawn Powers

SELinux and Ctrl-Alt-Del

I have two comments. The first one is more a complaint than a comment. In “Introducing Grive” in the December 2012 issue, the author flatly states “disable SELinux”. I find this to be very bad advice. The demonstration is on a CentOS 6 system, which does have a fairly good implementation of the strict policy. There's no real reason to disable SELinux. For applications where no policy exists, one can set SELinux to permissive mode (which would have been the correct advice), and with the help of the (SELinux) community have a new policy created. This would, IMHO, be far better advice.

The other comment is on the more or less unlucky discussion of Ctrl-Alt-Del for logging into Windows. This had a very practical and sound reason: the interrupt generated by Ctrl-Alt-Del could not be caught by any program and, thus, no fake login program for harvesting login credentials.


Mehdi Amin replies: First, I would like to thank Klaus for his comment.

Given past experiences, I came to the following conclusions.

The problem with SELinux for non-IT people is that it does not identify itself as the cause of permissions problems. In other words, the errors you get are not distinguishable from other more common errors, and SELinux is the last place you will look or for which you will be able to get answers publicly. SELinux enhanced local security by improving the isolation between processes and providing more fine-grained security policies.

For multi-user machines, this can be useful because of the more flexible policies, and it raises more barriers between users, so it adds protection against malicious local users.

For servers, SELinux can reduce the impact of a security vulnerability in a server. Where attackers might be able to gain local user or root privileges, SELinux might allow them to disable only one particular service. For typical home use, where you'll be the only user, you won't gain any security from SELinux.

Always keep in mind that a poorly understood security tool is a liability, because you might get a false sense of security if you become overconfident about its abilities, and there's a risk that you will misconfigure it and introduce a security hole.

Google Dart

I'm the author of the article “Introducing Dart, the New Web Language from Google” in the March 2013 issue. I wrote the article in late December and submitted the article in early January of this year. During the time I was writing it, I was using Dart M2 (version I made sure to have my colleagues check over my code, and I worked hard to make sure that everything was perfect!

“Best laid plans of mice and men often go astray.” These words are all too true for me, since only nine days before the release of the March 2013 issue, Google released Dart M3, and with it came a new, non-backward-compatible standard library API. Of course, I didn't see that it had released the new version until February 28, 2013, which was hours before the March issue was going to be sent to everyone.

So what was I going to do? After I wiped the stunned look of realization off of my face, I quickly worked to update all of the example code that was now broken to use the newest API. I posted an entry on my blog at jamesslocum.com/post/44259278296 where I describe what happened, and I explain the differences between M2 and M3 Dart. I also provide re-worked examples that can be run with the newest versions of Dart and Dartium.

I apologize to any reader who was confused or frustrated trying to run the examples listed in the article. I assure you that great care was put into writing them, and they work perfectly on the M2 release. I had no way to predict that such a large breaking change would occur right before the article went to print.

I still think you should give Dart a solid chance. Although the timing wasn't the best, the changes Google made were very good and moved Dart toward a more cohesive API. As any Rails developer knows, breaking changes can be hard, but they are usually for the best!

James Slocum

Photo of the Month

Here is “The March of the Penguins” sent to us by Kippie our niece (artist rendition).

Gary Artim

“The March of the Penguins” by Kippie

LJ Archive