A listing of random software, tips, tweaks, hacks, and tutorials I made for Ubuntu

How to fix lockdown error -5 on usbmuxd

When I plug my iPhone in (iOS 9), usbmuxd (and hence libimobiledevice-related software) runs just fine, but when I plug my older iPad in (iOS 5), I get this error:

[18:51:51.199][3] Connected to v2.0 device 1 on location 0x20009 with serial number ("random" string of numbers)
[18:51:51.867][1] preflight_worker_handle_device_add: ERROR StartSession failed on device (same "random" string of numbers), lockdown error -5

I spent quite a long time trying to fix this issue. I tracked down this file, that contains this line:


So it’s an SSL-related issue, and it happens with an older device, and not a newer one … figured it might be the certificates, and, since I haven’t connected my iPad to the internet for a while, decided to give that a shot. Same issue. But hey, it was fun being able to use Cydia! (at the time of writing, there is no public jailbreak for iOS >=9.2)

After a while of playing with certificates on my host computer (with the same luck), I decided to try compiling both libimobiledevice and usbmuxd with debug flags.

Right off the bat, I got my first (and only) compiler error: undefined reference to 'SSLv3_method' (or something like that).

Turns out that OpenSSL disables SSLv3 by default, for security reasons. After changing SSLv3_method to SSLv23_method (as per this patch) and enabling debug flags, I found that, indeed, the problem relied exactly where the compiler error was:

19:11:34 idevice.c:722 idevice_connection_enable_ssl(): ERROR in SSL_do_handshake: SSL_ERROR_SSL

Thankfully, libimobiledevice contains support for GnuTLS, which, also thankfully, still supports SSLv3! Although there were a few compiler errors because I’m guessing nobody really used the GnuTLS backend for some time, once it was built, I finally managed to make usbmuxd (and libimobiledevice-using software) recognize my iPad!

EDIT: libimobiledevice fixed the compiler errors upstream.

So, if you encounter this error, here’s how you fix it:

git clone
cd libimobiledevice
./ --prefix=/usr --disable-openssl
sudo make install

I hope this can help someone else with this issue! If you have any problems, feel free to leave a comment and I’ll try my best to help!

openlux 0.2.1 + roadmap

A few months ago, I wrote openlux as an open-source alternative to f.lux, similar to redshift, but different in goal and execution.

openlux 0.2.1 isn’t a particularly exciting release, but it fixes problems with graphics cards that support 10-bit displays .. something that openlux claimed to support, but, as it turns out, didn’t. After nvidia’s new driver update, I found that out the hard way (the screen went really weird, and at one point, totally black … not fun haha).

I also changed the logo slightly, I think it looks much nicer now! Here it is:


Now about the roadmap, I’m planning on adding these features later on:

  • Two new backends, DRM and RandR, to support both direct tty (DRM), and more graphics drivers (RandR) that don’t properly support XF86VM (what openlux currently uses as its main backend)
  • A GUI for automating openlux via cron (and also for using it directly)
  • A GUI for iOS that will support both scheduling and using it directly (similar to the feature above, but iOS doesn’t support cron)
  • iOS 9 support (apparently iOS 9 works in a different way for this … sadly, my iPhone isn’t jailbroken yet, so I can’t test it yet)


Explaining Javascript Closures Simply

Please note that this article might not be entirely accurate, it is simply meant as a very simple explanation that will get you in the right path to understand them. If you wish for a technically correct answer, see this question on Stack Overflow.

Javascript Closures tend to confuse people who aren’t used to Javascript (don’t feel bad if you’re in this category, Javascript is a weird language, I am certainly included in this category as well).

However, they’re really simple. But many guides tend to make them seem more complicated than they really are. Stack Overflow contains a wonderful array of answers that ended up leaving me more confused than when I started.

So, I’ll give the answer that I believe would have made it clearest to me: A closure in Javascript inherits the stack of the function that declared it. The stack is an object, in the sense that it only goes away when there are no more references.

If you understand what that means, then great! Hopefully this helped! If not, I’ll explain :)

First, a closure in javascript is basically a ‘lambda’, a sort of ‘anonymous function’, and if these terms confuse you (don’t feel stupid if they do, I think we all suck with terms), here’s what it looks like:

setTimeout(/* This is a closure! --> */ function() {
    alert("Hello world!");
} /* <-- End of the closure */, 1000);

You’ve probably seen these everywhere in Javascript.

Now, the “stack” (in Javascript) is basically the local variables in a function. For example:

function hello() {
    var first = "Hello";
    var space = " ";
    var second = "world!"

    var message = first + space + second;

    /* first, space, second, and message are all part of the "stack" */

Technically, every function in Javascript is a closure, so therefore, every function inherits the stack of the function that declared it, not the stack of the function that calls it.

In other words:

function hello() {
    var message = "Hello world!";

    return function() {

var message = "Farewell planet";

var closure = hello();
closure(); /* This will output "Hello world!", because it inherits hello's stack */

But doesn’t the stack end once hello() has finished running? Nope, the stack is like an object (it might actually be one, I’m not sure), in the sense that the object will live so long as there is a reference to it. The closure has a reference to it (every object has a reference to their stack), and therefore, the stack is still alive.

What if a closure makes a new variable .. will that change be reflected in the stack of the old function? Nope, every function makes a new stack, that inherits the parent stack (the stack of the parent function that declared this function). For example:

function hello() {
    var first = "Hello";
    var second = "world!";

        function() {
            first = "Goodbye";      // Modifies 'first' in the parent stack

            var second = "planet!"; // Notice the "var" .. this makes a new variable
                                    // in the _current_ stack.
                                    // Any future reference to 'second' will refer
                                    // to the variable in the _current_ stack, not
                                    // the variable in the parent stack.

            second = "galaxy!";

            var message = "Hi";     // This was declared in the current stack, message
                                    // will not be declared in the parent stack.
        function() {
            console.log(first);     // "Goodbye"
            console.log(second);    // "world!"
            console.log(message);   // message isn't declared
    ].forEach(function(x) {x()});   // Runs these functions, one after the other

That’s about it!

I hope this helped you to understand how closures worked in Javascript. If you’re still confused, feel free to leave a comment!

I’m not an expert on this, and certainly, this guide isn’t meant as an expert technical analysis of how closures work, it’s mainly just meant as a (hopefully) simple bird’s-eye view of how  they work. As I mentioned a few times before, you can find a more detailed explanation at Stack Overflow.

Download videos online with Inject2Download

and I swear this blog hasn’t been hijacked . Apologies for the clickbait title, although, in all honesty, I’m not sure how else to word it … suggestions? :)

Most video download scripts I’ve seen generally tend to rely on some download server that does magic behind the scenes, which may or may not work, among other issues (ads, loading times, etc.). I also don’t like the fact that I can’t really know what’s going on behind the scenes (one of the reasons I use free software).

Thing is, for many websites that embed videos (that don’t host content with their own proprietary players, i.e. not youtube, vimeo, wistia, dailymotion, etc.), they have the direct video URL somewhere in the javascript (plainly readable or obfuscated).

Since most websites use the same player engines to play their videos (jwplayer, flowplayer, or video.js), all that is needed to do is to inject code into those engines when the page is loaded that will capture the video URL and somehow share the URL with the user.

I originally started writing this using Chrome, until I found out that Chrome actually doesn’t support injecting code directly after a library is loaded (which Firefox does), so I ended up making this only Firefox-compatible. I tried to sort of “race” the code so as to try to run the code as soon as possible after the libraries were loaded, but it only worked a fraction of the time, and plus it slowed down the webpage heavily.

Inject2Download is a user script, so you’ll need Greasemonkey to run it. If there’s enough interest, I’ll make it a proper extension later :)

Download and install it here:


What you’ll (hopefully) notice is that when you go to a website that hosts a video player, a little box will pop up at the top-left corner of the page (you might have to scroll up to see it), containing one or more URLs.

Some websites host ads on the player, and it’s sometimes (although rarely, thankfully) a bit difficult for the script to know which is an ad, and which is a legitimate video, so just use common sense and avoid URLs with “ads” or other suspicious text as part of them :)

If you have any issues with this, please feel free to let me know, either on here or via github, I’d be happy to help!


trivial-require: Closure-friendly Browserify(ish)

… and that title is about as accurate as saying that D is a superset of C, but the most accurate one I could think of that could fit in a relatively small space of text.

Before I explain further, I’ll explain my use-case scenario. I’m writing a web app that is meant to be used on my iPhone. 3G can be used up really quickly by browsing websites, and I plan on using the app a lot, so I need to make sure that the website uses as little bandwidth as possible.

Google’s Closure Compiler is very good at minifying Javascript code (the best I know of), and, under normal circumstances, it works just fine. Thing is, I’m writing the server in node.js, and I want to be able to share the same codebase with both the server and the client. With a tool like Browserify, this becomes very easy.

Problem is, Closure and Browserify don’t match very well. Sure, you can use Closure on a Browserified piece of code, but it doesn’t optimize nearly as well as it could. Few functions are properly inlined or evaluated, many variable and property names stay intact, and there’s a lot of needless code around it.

Use case scenario done. Now on to trivial-require (this line is for the TL;DR people :P)

I wrote trivial-require as a very quick and dirty hack for the project I was working on. It might not be ideal for everyone, but hopefully some people will be able to find it useful as well :)

trivial-require sort of functions like Browserify, in the sense that it will turn node.js code into browser code, and, if the winds are in your favour, it might work.

Okay, that might have been a bit of an exaggeration. This following line will sum up almost exactly what it does (bolded for the TL;DR folk, again)

trivial-require will literally include the contents of the require()d file at the spot where it is require()d. module.exports is entirely disregarded

No extra code is added around it. Literally the only difference between this and C’s #include directive is that this only will include a file once. In other words, var module = require('file'); var module2 = require('file'); will result in file.js being included once (both lines are removed in the output file).

This works in a very different way from the way that browserify and node.js work. But, it is possible to write code that works both with node.js and trivial-require.

Before I go to this though, I’ll explain how to install/run it:


sudo npm install -g trivial-require


trivial-require script.node.js > script.browser.js

Now that that’s done, let’s go to the guidelines on using it:

Do not use ambiguous variable names. It might be overridden by a future module.

// Wrong
var Logger = require('./Logger')("ModuleName");

// Correct
var Logger_ModuleName = require('./Logger')("ModuleName");

Do not use module.exports as a means for writing a function (or other). Any line containing module.exports is deleted.

// Wrong
module.exports = function() {
    console.log("Hello World");

// Correct
function HelloWorld() {
    console.log("Hello World");

module.exports = HelloWorld;

Use the same module name when require()ing a file. Each file is literally included, and both require() and module.exports lines are deleted.

//// Wrong

// HelloWorld.js
function HelloWorld() = {
    console.log("Hello World");

module.exports = HelloWorld;

// index.js
var GreetPlanet = require('./HelloWorld');

//// Correct

// index.js
var HelloWorld = require('./HelloWorld');

require() in the global scope. Caching might hurt you later.

// Wrong
function my_function() {
    var HelloWorld = require('./HelloWorld');

// Correct
var HelloWorld = require('./HelloWorld');

function my_function() {

require()s containing non-relative pathnames will be removed. Use your own modules instead

// Wrong
var utf8 = require('utf8');

var encoded = utf8.encode("Hello World");

// Correct
var is_node = false;
if (typeof window === "undefined")
    is_node = true;

var encoded;

if (is_node) {
    var utf8 = require('utf8');
    encoded = utf8.encode("Hello World");
} else {
    encoded = unescape(encodeURIComponent("Hello World"));

And that’s about it! I hope that trivial-require might be useful for you, and that this guide is clear enough :) If you need help with anything, feel free to leave a comment, and I’ll try to help!

Fun obfuscation in openlux

I was working on a free software alternative to f.lux named openlux a while ago, and I wasn’t working on any interesting aspects of the program, just rewriting functions, which gets a bit tedious after a while, so I decided to try writing one part of the code in a slightly different manner, for fun! :D

The code is supposed to add a variable to another if a character is ‘+’, and subtract it if the character is ‘-‘. Here would be how one might implement this:

int a = /* something */;
unsigned short b = /* something ... note that b is a smaller data type than A, this is important */;
char chr = /* '+' or '-' */

if (chr == '+')
    return b + a;
    return b - a;

After a few hours (maybe even a day, I’m not very good at this :P), I came up with this instead:

a = (0x80000000 | a) ^ (0x80000000 - !!(chr - 43));
if (a & 0x80000000) a++;
return a + b;

To dissect this, let’s start with the easiest part (other than return a + b;, of course :P): !!(chr - 43).

43 is simply the value of ‘+’. Yes, okay, that was a bit cheap :P So, what !!(chr - '+') does is that it will return 0 if chr == ‘+’, 1 otherwise. This could be have been rewritten as (chr != '+').

Easy part out of the way, let’s look at how numbers are encoded, via example, in binary:

00000000 = 0
00000001 = 1
00000010 = 2
00000011 = 3

So far so good, right? But what about when we reach 10000000? If it’s an unsigned byte, it will return 128 (2^8). If it’s signed, however, it will return -127:

01111111 = 127
unsigned 10000000 = 128
signed   10000000 = -127
unsigned 10000001 = 129
signed   10000001 = -126

In both cases, the number will keep getting larger after 10000000, but if it’s signed, it will have wrapped around to -127.

Let’s see larger values:

unsigned 11111101 = 253
signed   11111101 = -3
unsigned 11111110 = 254
signed   11111110 = -2
unsigned 11111111 = 255
signed   11111111 = -1

Notice that the largest value for the signed number is not 0, but rather, -1. This is important. If it was 0, then it would mean inverting the bits of a number would make it negative (i.e. ~n == -n).

So what would inverting the bits do?

11111111 = -1
00000000 = 0

11111110 = -2
00000001 = 1

11111101 = -3
00000010 = 2

11111100 = -4
00000011 = 3


Notice a pattern here? If we want to turn a negative number positive, we can do it via (~n) - 1. Vice-versa, it’s (~n) + 1.

Alright, back to the code!

(0x80000000 - (chr != '+'))

0x80000000 can be represented in binary as 10000000000000000000000000000000. In other words, the sign bit for a 32-bit integer. So if chr == '+', it will simply evaluate as 0, and therefore, keeping 0x80000000 intact. Otherwise, it will turn it into 0x7fffffff, which is equivalent to 01111111..., or ~0x80000000.

(0x80000000 | a) simply returns a, with the sign bit on.

Now, to deal with the xor part, let’s use a few examples to clarify:

chr = '+';
(0x80000000 | a) ^ (0x80000000 - (chr != '+'));
(0x80000000 | a) ^ (0x80000000 - 0);
// 0x80000000 ^ 0x80000000 cancel each other out, leaving us with 'a', unchanged (assuming a < 0x80000000)

chr = '-';
(0x80000000 | a) ^ (0x80000000 - (chr != '+'));
(0x80000000 | a) ^ (0x7fffffff);
// assuming a < 0x80000000, this is equivalent to ~a, because the sign bit is left on, while every bit of a is inversed
// as we discussed, ~a is equal to ((-a) - 1)

if (a & 0x80000000) a++; checks if the sign bit is set (i.e. a < 0), and if so, increments a so that it gets the correct (negative) value, for the reasons I explained earlier.

Lastly, all we have to do is return a + b;, which should hopefully be pretty obvious :P

Let’s recap quickly

If chr == '+', a is left unchanged, and the result is simply a + b

If chr != '+', a‘s bits are inverted, and then incremented so that it can be equivalent to a = -a, so the result would be (assuming a’s original value, not the inverted+incremented value): -a + b or b - a.

I hope that you found this interesting, or at least fun to read! I’m sorry if this isn’t very clear, I’m sort of writing this to try and get to sleep, I’ll edit it tomorrow :)

Injecting code into running process with linux-inject

I was about to title this “Injecting code, for fun and profit”, until I realized that this may give a different sense than I originally intended… :P

I won’t cover the reasons behind doing such, because I’m pretty sure that if you landed on this article, you would already have a pretty good sense of why you want to do this …. for fun, profit, or both ;)

Anyway, after trying various programs and reading on how to do it manually (not easy!), I came across linux-inject, a program that injects a .so into a running application, similar to how LD_PRELOAD works, except that it can be done while a program is running… and it also doesn’t actually replace any functions either (but see the P.S. at the bottom of this post for a way to do that). In other words, maybe ignore the LD_PRELOAD simile :P

The documentation of it (and a few other programs I tried) was pretty lacking though. And for good reason, the developers probably expect that most users who would be using these kinds of programs wouldn’t be newbies in this field, and would know exactly what to do. Sadly, however, I am not part of this target audience :P It took me a rather long time to figure out what to do, so in hopes that it may help someone else, I’m writing this post! :D

Let’s start by quickly cloning and building it:

git clone
cd linux-inject

Once that’s done, let’s try the sample example bundled in with the program. Open another terminal (so that you have two free ones), cd to the directory you cloned linux-inject to (e.g. cd ~/workspace/linux-inject), and run ./sample-target.

Back in the first terminal, run sudo ./inject -n sample-target

What this does is that it injects the library to a process by the -name of sample-target. If instead, you want to choose your victim target by their PID, simply use the -p option instead of -n.

But … this might or might not work. Since Linux 3.4, there’s a security module named Yama that can disable ptrace-based code injections (or code injections period, I doubt there is any other way). To allow this to work, you’ll have to run either one of these commands (I prefer the second, for security reasons):

echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope # Allows any process to inject code into any other process started by the same user. Root can access all processes
echo 2 | sudo tee /proc/sys/kernel/yama/ptrace_scope # Only allows root to inject code

Try it again, and you will hopefully see “I just got loaded” in-between the “sleeping…” messages.

Before I get to the part about writing your own code to inject, I have to warn you: Some applications (such as VLC) will segfault if you inject code into them (via linux-inject, I don’t know about other programs, this is the first injection program that I managed to get working, period :P). Make sure that you are okay with the possibility of the program crashing when you inject the code.

With that (possibly ominous) warning out of the way, let’s get to writing some code!

#include <stdio.h>

void hello() {
    puts("Hello world!");

If you know C, most of this should be pretty easy to understand. The part that confused me was __attribute__((constructor)). All this does is that it says to run this function as soon as the library is loaded. In other words, this is the function that will be run when the code is injected. As you may imagine, the name of the function (in this case, hello) can be whatever you wish.

Compiling is pretty straightforward, nothing out of the ordinary required:

gcc -shared -fPIC -o hello.c

Assuming that sample-target is running, let’s try it!

sudo ./inject -n sample-target

Amongst the wall of “sleeping…”, you should see “Hello world!” pop up!

There’s a problem with this though: the code interrupts the program flow. If you try looping puts("Hello world!");, it will continually print “Hello world!” (as expected), but the main program will not resume until the injected library has finished running. In other words, you will not see “sleeping…” pop up.

The answer is to run it in a separate thread! So if you change the code to this …

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>

void* thread(void* a) {
    while (1) {
        puts("Hello world!");
    return NULL;

void hello() {
    pthread_t t;
    pthread_create(&t, NULL, thread, NULL);

… it should work, right? Not if you inject it to sample-target. sample-target is not linked to libpthread, and therefore, any function that uses pthread functions will simply not work. Of course, if you link it to libpthread (by adding -lpthread to the linking arguments), it will work fine.

However, let’s keep it as-is, and instead, use a function that linux-inject depends on: __libc_dlopen_mode(). Why not dlopen()? dlopen() requires the program to be linked to libdl, while __libc_dlopen_mode() is included in the standard C library! (glibc’s version of it, anyways)

Here’s the code:

#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <dlfcn.h>

/* Forward declare these functions */
void* __libc_dlopen_mode(const char*, int);
void* __libc_dlsym(void*, const char*);
int   __libc_dlclose(void*);

void* thread(void* a) {
    while (1) {
        puts("Hello world!");

void hello() {
    /* Note For some reason,
       using the symbolic link ( will not work */
    void* pthread_lib = __libc_dlopen_mode("", RTLD_LAZY);
    pthread_t t;

    *(void**)(&pthread_lib_create) = __libc_dlsym(pthread_lib, "pthread_create");
    pthread_lib_create(&t, NULL, thread, NULL);


If you haven’t used the dl* functions before, this code probably looks absolutely crazy. I would try to explain it, but the man pages are quite readable, and do a way better job of explaining than I could ever hope to try.

And on that note, you should (hopefully) be well off to injecting your own code into other processes!

If anything doesn’t make sense, or you need help, or just even to give a thank you (they are really appreciated!!), feel more than free to leave a comment or send me an email! :D And if you enjoy using linux-inject, make sure to thank the author of it as well!!

P.S. What if you want to change a function inside the host process? This tutorial was getting a little long, so instead, I’ll leave you with this: and specifically . I’ll try to make a tutorial on this later if someone wants :)

How to remove the annoying YouTube lightsaber sound

Google pulled off a clever marketing stunt for Star Wars, allowing you to “choose your side of the force” – which consequently changes various Google products to fit the theme accordingly.

One change they introduced added lightsaber sound effects when you hover over the volume icon on a Youtube video. While being a cute gimmick, I found this to be quite annoying, especially when listening to music, so I spent the morning trying to make a small script that would disable it.

I thought I would share it, since I’m guessing there are others who also find this annoying

It works most of the time, but if you hover over the volume icon before the script has a chance to run, the sound will still happen. Just wait a second or two, and it will work :) Also, if you just installed the extension, you will need to reload the page.

I uploaded a unified codebase to github, mainly since I didn’t like constantly having to copy files from/to various codebases :P Here it is, if anyone’s interested:

Why Openlux instead of Redshift?

First, I want to clarify that this is not a post trying to show that one is better than the other unequivocally. This is, instead, a post trying to show my reasons for writing openlux, and the differences between both softwares. I’m sure that many people will prefer the way that redshift works, over the way that openlux works, and that’s awesome!! The purpose of this post is, mainly, to show the differences, and hopefully help you decide which is better for your circumstance :)

My initial reason for writing openlux was because f.lux didn’t work for me, for various reasons (as I outlined in the first post about it) … I was actually unaware of redshift. There were a few people who linked me to it, and I immediately felt slightly disappointed that I hadn’t done my research before (would have saved me quite a bit of work!). Looking into it though, it’s not what I was looking for, and it has some of the issues that made me switch away from f.lux.

Redshift’s mode of operation is different than openlux’s. It primarily functions as a daemon, changing the color temperature automagically, depending on your timezone. This is a really handy feature, however, you don’t have much ability to configure the times. If you don’t have insomnia, and have a regular sleeping schedule, this is probably perfect. You tell it where you live, and it will change the screen color temperature throughout the day, in order to match the light you would receive if you were outside at that time (except at night, of course =P). But in my case, I can stay up until 4-5am, unable to sleep at all. Having the screen automatically change to a higher color temperature when I’m trying to go to sleep is most definitely not what I need. Now I could change the timezone every so often, but I’d rather have something in which I control when the screen color changes, instead of having to work against the program. I am aware that redshift has an option for manually changing the color temperature, but you don’t have much control over other options (such as animating to it, or individual control over RGB channels).

Redshift also uses color tables in order to compute the RGB values from kelvin temperatures. This allows for maximum accuracy within the range it provides (1000-25100K), however, it doesn’t allow anything outside of the range. On the other hand, openlux, works using Tanner Helland‘s algorithm, which allows for a theoretically infinite (practically 0-232, because it’s stored in a 32-bit integer), but less accurate result. Personally, I prefer using an algorithm, but there are definitely things to say about using a color table instead. The algorithm is pretty accurate (I think it’s a maximum of ~3-5% off of the original value), but if you’re within the range that redshift provides, it’s always nice to have 100% accuracy!

The main philosophical difference (that influences how the programs evolve) between redshift and openlux is the goal: redshift is more oriented towards being a standalone, fully-featured program, while openlux is oriented towards being a program that only does one task (change the screen color temperature), and focuses on that one task. It leaves tasks such as changing the color temperature in accordance with the timezone to other programs specialized for this (such as cron), or manually. Redshift tends to go more on the side of “run it, and forget about it”, while openlux leans more on giving the user maximum control and flexibility.

There’s definitely something to be said about both philosophies, and different users will appreciate different philosophies. I personally prefer the one of having full control at all times, but there are many users who would prefer to just have the program manage it for them automagically.

If you’re not sure which to use, try both! See which one works best for you. After all, GNU/Linux is all about choice :)

If I’ve made any mistake in this article, please let me know. This post is most definitely not about saying that one software is better than the other. While I, of course, prefer openlux, I want this to be a fair comparison of both softwares, so that users can better decide which software they want to use for themselves.

Openlux 0.2 beta – Animations, iOS port

I wrote openlux around 2 and a half weeks ago, as a simple, libre alternative to f.lux that addresses a few issues I’ve encountered with it. I’ve since used it everyday, and I’ve actually noticed an improvement in my sleep!

However, my iPad still uses f.lux (or, until today, at least). No, in this case, I’m not worried about the fact that f.lux is proprietary (it’s an iPad), but earlier, when my sleep was really messed up (and by messed up, I mean, I was going to sleep at 7-8am), f.lux would automatically switch to 3400K (instead of 2300K), which definitely didn’t have a positive impact on my sleep. Also, it only goes down to 2300K, doesn’t allow much customizability, and doesn’t always work how I want it to work, etc.

So after spending quite a long time (basically ever since I released the first version of openlux) working on the port, it finally works!!! It doesn’t work as well as I wanted it to (multiple colors output the same value, compressing the color range … I tried lerping values, but it ended up giving garbage), but at least it works!

Animations literally took about the last hour of developing this version (in other words, barely any time at all, compared to the time needed to develop the iOS port), since, luckily, I only encountered one bug while making it. The point of animations is not for visual bling, but rather to make it easier on the eyes if it’s run automatically (e.g. via cron).

Other than those, there are a few minor features, such as optional relative adjustment of colors (“-b 10” will set the blue channel to 10, “-b +10” will add 10 to the blue channel, and “-b -10” will remove 10), and saving/resetting gamma values (mainly just a by-product of working on the iOS port).

If anyone would be interested in testing this on their iDevices, I would really appreciate it ^^ Though it works fine on my 1st generation iPad, I don’t know if it will work on other devices too. I wrote instructions on how to compile and run it here: :) I’m not aware of this being able to cause any permanent damage to your device (my device works fine now, even after the display being severely messed up multiple times), but if you’re scared, stick with f.lux for now. Quick note: it doesn’t work on iOS <4, since it needs to retrieve the gamma table (which iOS versions <4 don’t support).

To wrap up, here’s a few examples of the new features that come with openlux 0.2:

openlux -k 1000 -a 10000         # Animates to 1000K in 10 seconds (10000 milliseconds)
openlux -k 1000 -a 100000 -d 100 # Animates to 1000K in 100 seconds, with a delay of 100 milliseconds per "frame" (less CPU usage)
openlux -k 1000 -g +10           # Sets the color temperature to 1000K, but adds 10 to the green channel
openlux -R                       # Resets to the last saved gamma table (openlux automatically saves the gamma table the first time it's run per boot)
openlux -s                       # Saves the gamma table