handyfloss

No matter what they say, [[Hibernate (OS feature)|hibernating]] Linux laptops has always been a problem. I managed to get my MacBook to [[sleep mode|suspend]] to RAM quite reliably without much of a hassle. It suspends when I close the lid, and it resumes when I open the lid back. I even configured it to suspend when battery is critically low. This way, and due to the really low power consumption while suspended, I can safely forget my laptop on and unplugged for extended periods of time, and the worst that can happen is that I will have to resume it. A huge difference from the nasty surprise of finding it off and losing all the information not saved to disk.

However hibernating to disk is a whole different business. I never managed it to work, and that was an itch I wanted to scratch. Finally I managed, with the following recipe.

HowTo

First, make sure that you have enough [[paging|swap space]] available in disk. In Linux you generally create a swap [[disk partitioning|partition]] when installing the OS. The old adage states that one should make the swap partition twice as big as the RAM memory of the computer. With modern computers this is both unnecessary (because the big RAM makes sure you’ll never run out of it, and if you do, you are screwed anyway) and wasteful (if you have a 4GB RAM, it means that you dump 8GB of disk space). However, if you intend to hibernate your computer, all the information in the RAM memory has to be copied to the hard disk, so you sure need at least as much swap as RAM (but not twice).

Second, you need to use the correct tool. I use [[Xfce]] as desktop environment under Ubuntu, and the Exit menu presents me with six options: “Switch user”, “Log out”, “Restart”, “Shut down”, “Suspend” and “Hibernate”. I think that the latter two make use of the tools in the acpi-support package. The suspend action seems to work OK, but the hibernate one doesn’t (for me). It runs the command /etc/acpi/hibernate.sh, and it gives me problems. Thankfully I found some utilities that work reliably, namely pm-utils.

The pm-suspend command seems to work as correctly as the “Suspend” button in the Exit menu of Xfce. The pm-hibernate, on the other hand, works perfectly, unlike the “Hibernate” button. The drawback is that only root can run it. My solution is to put a launcher button in the Xfce task bar, that will run “gksudo pm-hibernate”. This way I am asked for my password and, if sudo is correctly set up, pm-hibernate will run.

More info

Sometimes it is very interesting to run some commands at suspension/hibernation moment, or at resuming/thawing. One such command is [[hdparm]], with which you can fix the long known load/unload cycle problem (you can google about it). Another one is one to fix a problem that apparently appears on MacBooks: the [[touchpad]] is lost when the computer wakes up back. The keyboard works, and USB mice work, but the touchpad doesn’t. This problem can be fixed by reloading the appletouch [[Loadable kernel module|kernel module]]:

You can fix both issues above by creating a file named, e.g., 99-macbook_fix, in /etc/pm/sleep.d/, and making it executable. Then write in it the following:

As you can see on the right side tab of this page, Ubuntu 8.10 has just been released!

Pick a mirror and download. Or better yet, do it through BitTorrent.

Hey, October almost passed and I didn’t write the montly report on LWD. I might make it bimontly, to produce less spam in the blog. You can read an intro for my Linux World Domination project in this May 2008 post.

As usual D2D means “days to domination” (the expected time for Windows/Linux shares to cross, counting from Feb 3, 2008), and DD2D means difference (increase/decrease) in D2D, with respect to last report. CLP means “current Linux Percent”, as given by last logged data. The new datum DD means domination day (in YYYY-MM-DD format).

As a new feature, I am now fitting the curves (to predict Windows/Linux crossing) to first degree polynomials, but taking only the last N points so that the [[Coefficient_of_determination#Definitions|coefficient of regression]] is close to 1 (yes, I am being purposely unclear and arbitrary on this subject).

OK, the data seems discouraging. The crossing day (DD) seems to be further away every month, instead of closer. Recall however that the only (half) reliable data are the current (and past) percents. All the rest is speculation, and the fits change wildly depending on the function used to make them, and the number of points fit.

Starting with this month’s issue, I might post pictures of the evolution plots. Today I’m showing the plots for Einstein@home. Next month: Malaria@home.

Number of hosts percent evolution for Einstein@home (click to enlarge)

Accumulated credit percent evolution for Einstein@home (click to enlarge)

Leído vía Menéame, un vídeo hecho por alumnos de una escuela de Ordizia, mi pueblo natal:

It is common to hear that recent advances in the Linux desktop, such as [[Compiz Fusion]], are more of a fancy but useless aesthetic contribution to the desktop. While it may be true for many of the CF features, it is no less true that you never know when a given effect will turn out to be useful.

In this post I want to praise the Enhanced Zoom Desktop plugin. It turned out to be of great use for me in the following situation. I wanted to run [[Diablo II]] in my laptop (yes, it runs in Linux, under Wine). The native resolution of the program (640×480 or 800×600) is lower than that of my screen (1280×800), so I have two options: to execute it in windowed mode, or fullscreen. In windowed mode the window occupies less than 2/3 of the 13.3″ screen, wasting space and making it unnecessarily small. Fullscreen mode seems to be better, but it isn’t. Since the width/height ratio is smaller for Diablo than for the screen, the former will be stretched horizontally, distorting the images (everything looks more squat). Fullscreen mode also gave me other problems, like crashing more easily when alt-tabbing.

Here is where the zooming of Compiz Fusion comes in handy. Apart from an arbitrary zoom (using the mouse wheel while pressing the Super key, a.k.a. windows key), there is a handy shortcut (Super+r) that zooms up to the point of the screen under the cursor occupying the whole screen. When zooming, the movement of the mouse makes the zooming “window” to move around, showing different parts of the desktop. To avoid it (clearly unwanted if we want to stay inside the Diablo window), we have another shortcut: Super+l. This shortcut toggles on and off the “zooming lens follows the mouse” movement.

So now, if I want to play Diablo I open it in windowed mode, then put the cursor inside the window, then hit Super+r, then Super+l, and I have a Diablo window as big as possible to fit in my screen, preserving height/width ratio, and keeping the mouse inside the window.

I am a heavy user of the [[Grace (plotting tool)|Xmgrace]] plotting program, and I love it. An operation very ofter used is to scale the X and Y axes to our liking, to show different parts of our data in the resulting plot. You can do that from the command line by setting the “world” of the graph, providing four numbers as X,Y boundaries:

% xmgrace -world xmin ymin xmax ymax file.dat

Apart from setting the maximum and minimum values for X and Y, we can make use of the autoscale option to selectively show some ranges. The four options to autoscale are:

• none – show the X,Y ranges defined by the “world” variable (if not set, the default is “0 0 1 1”).
• xy – forget about “world” data, make plot range in X and Y enough to plot all data in input.
• x – autoscale X to show all data, but respect Y given by “world”. This means that if a point is not shown because it lies outside the Y range, then it doesn’t count to force X autoscale. This is a wee bit trickier than it sounds.
• y – see previous point, with X and Y swapped.

But Xmgrace is not only about [[command-line interface|command line]], or even [[Graphical user interface|GUI]]. You can write a .agr file (for example by saving a plot from the Xmgrace GUI), and manipulate it so that the following command:

% xmgrace file.agr

will bring up a plot with all the data and formatting we have put into the .agr file. It’s really handy to save a file as-is.

Now, the syntax for inputting the world in the .agr is well known:

@ world xmin, ymin, xmax, ymax

where xmin etc. are floating point numbers.

The problem is how to hardcode the autoscale feature into the .agr. I had always been forced to do:

% xmgrace -autoscale none file.agr

from the command line, because I couldn’t find out how to include it in the .agr. Finally I did find it, and that’s the main reason of this post. The syntax is explained in the manual at the Xmrace site, but I found it after googling for agr files containing “autoscale” in them. The line to include seems to be:

@ autoscale onread none

A .agr containing the above line will produce, when called as follows:

% xmgrace file.agr

the same output as a file not containing it, when called as follows:

% xmgrace -autoscale none file.agr

A request from a friend made me face the problem of converting a color [[Portable Document Format|PDF]] into a [[grayscale]] one. Searching the web provided some ways of doing so with [[Adobe Acrobat]], via some obscure menu item somewhere.

However, the very same operation could be undertaken with free tools, such as [[ghostscript]]. I found a way to do it in the YANUB blog, and I will copy-paste it here, with a small modification.

Assuming we have a file called color.pdf, and we want to convert it into grayscale.pdf, we could run the following command (all in a single line, and omitting the “\” line continuation marks):

I prefer the above to YANUB’s version below (in red what he lacks, in blue what I lack), because a shell operation is substituted by some option(s) of the command we are running:

A sample [[Perl]] script to alleviate the tedious writing above:

Assuming we call the Perl script “togray.pl”, and that we have a color file “input.pdf”, we could just issue the command:

and we would get a grayscale version of it, named “input_gray.pdf”.

I recently updated the [[MediaWiki]] installation in one of my [[DreamHost]] domains from 1.12 to 1.13, and I started to see the following error messages when trying to edit/save pages (the capital letter triplets used for privacy):

Database error

A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was:

(SQL query hidden)

from within function “Article:getHiddenCategories”. MySQL returned error “1146: Table XXX.YYY_page_props’ doesn’t exist (mysql.ZZZ.AAA)”.

After a Google search that yielded only two results, I checked a mediawiki.org page talking about the subject. The (maybe obvious) reason for my error was that I hadn’t run the MediaWiki update script, as one should after any upgrade.

The procedures is outlined in this other mediawiki.org page. However there is a little catch: the [[PHP]] version (at least in my case) accessible in the shell of the server where my wiki is is 4.4.8, but the MediaWiki update script needs PHP5. No problem, I checked the DreamHost wiki, and found out that for PHP5 I could use the following executable: /usr/local/dh/cgi-system/php5.cgi.

Running that executable on the corresponding update.php script (after setting up AdminSettings.php as told to), everything was OK again.

Ups! August passed, my holidays finished, second work week… and I haven’t written much lately. I will partially fix that by updating my Linux World Domination project (you can read this May 2008 post for an intro).

As usual D2D means “days to domination” (the expected time for Windows/Linux shares to cross, counting from Feb 3, 2008), and DD2D means difference (increase/decrease) in D2D, with respect to last report. CLP means “current Linux Percent”, as given by last logged data.

I use [[Inkscape]] to do many of the drawings for my articles and talks, and have come across an irritating problem: I could not include [[LaTeX]] formulas on it. I have googled a bit about it, and the first match already led me to a bug report, where a comment by Kees Cook gives a fix that I quote below:

% cd /usr/share/inkscape/extensions
% curl -s 'http://launchpadlibrarian.net/12978623/eqtexsvg.py.patch' | sudo patch -p0

The bug affects (and the patch fixes) Inkscape 0.46 on [[Ubuntu]] Hardy Heron and [[Debian]] Lenny (that I know of).