Tag Archives: BASH

Fixing ncurses5 to ncurses6 Dependency Issues on Arch Linux

This post is alternatively titled: “How to resolve error while loading shared libraries: libncursesw.so.5: cannot open shared object file: No such file or directory”.

While attempting to do a recent system update, I ran into two problems:

  1. pacman was not downloading any packages due to an out-of-date gnupg package.
  2. Trying to install the gnupg package manually resulted in the alternative title of this post.

All of this was because I decided to run sudo pacman -S libncurses in order to get my conky working properly. Turns out a lot more programs rely on libncurses than I previously realized.

The problem gave me more of a headache than thought it would, but I eventually solved the issue. Here’s how:

  1. Since I recently upgraded libncurses through pacman from version 5 to version 6, the old version was still saved in the cache in /var/cache/pacman/pkg
  2. I extracted the cached version of libncurses by using sudo mkdir tempNcurses && sudo tar -xvf ncurses-5.9-7-x86_64.pkg.tar.xz -C tempNcurses
  3. I then copied the resulting binary into the libraries folder with sudo cp tempNcurses/libncursesw.so.5.9 /usr/lib
  4. I then made a symbolic link with the file specified in the error messages with sudo ln -s /usr/lib/libncursesw.so.5.9 /usr/lib/libncursesw.so.5

After this, everything worked as expected! I was able to manually update GnuPG and then update everything else that had a dependence on ncurses

Visualizing my Operating System Use

In my work, home, and play life, I constantly switch operating systems. If I want to play games, I use Windows. If I want to get some hardcore development done, I use Linux. If I want to casually browse the internet, I use my mac. But the question remains: How often do I use each operating system?

The Tool

Being a software developer, I thought that the best approach to answering this question would be to create a tool to do it for me. I would call it OSTracker (Short for Operating Systems Tracker – An extremely advanced acronym that definitely required this parenthetical explanation). Originally, the plan was to have a service that could run on any operating system that tracked how long I was on the computer. These metrics would then be uploaded to a centralized remote repository and would be parsed and analyzed by some sort of scripting language, that would then display the results in a semi-pretty format.

In order to create something that could easily be run on any operating system that I would pickup, I thought of creating the service in Java. The service could then be called with the following calling conventions:

java ostracker <login/logoff>

This would be extremely useful because this would also allow me to easily port the project from Linux to Windows, Android, or any other modern operating system that I may come across.

The Unfortunate Lack of Direction

Unfortunately, my laziness got the best of me. After all, I did not need to worry about having a constantly running service, as all I needed to keep track of was the name of the operating system, the time of the event, and whether or not the event was a log off or a log on. Since all I needed to do was push these metrics once, I decided that it would be better if everything was handled on the remote repository itself.

Thus, I created a PHP Servlet that would process all events. The servlet is pretty simple, it essentially accepts the aforementioned details as parameters and plops them into a file on the server if they should be there.

How does the servlet know if the information should be there? Well, if the previously tracked action is one that makes sense in relation to the new action. For instance,

  • You just logged off Windows, your last action was logging off Windows. This pair of events doesn’t really make sense.
  • You just logged off Windows, your last action was logging on Windows. This pair of events makes perfect sense.
  • You just logged onto Linux, your last action was logging off of Windows. Again, this makes perfect sense. I just switched operating systems.

Now, I wanted to give the system the ability to track when I was on many operating systems at the same time (assuming multiple computers, I suppose), so the servlet handles that case well.

  • You just logged onto Linux, your last action was logging onto Windows. No problem.

The datafile is arranged in a format of <operatingSystem><time><action> and different events are delineated with a newline character. Thus, the PHP file just has to use all the information from the last event in order to determine if the next event is able to be processed. If so, a 1 is returned. If not, a 0 is returned. Here’s the code:

$actions = explode("\n", file_get_contents($filename)); 
$actions_count = count($actions) - 2; 
$lastAction = $actions[$actions_count]; 
if (strstr($lastAction, $os) == FALSE || strstr($lastAction, $action) == FALSE)
  $resp = file_put_contents($filename, "$os$time$logaction\n");
  echo 1; 
  echo 0; 

As you can see, it’s extremely simple.

The Client-Side


Now that I had something that was running on the server, I needed something to actually call the PHP file in order to push the metrics onto the server. Again, I considered writing this in Java as it would provide me with the ease of portability. However, laziness got the best of me. I decided to write proprietary scripts.

For UNIX, I wrote a bash script. The script is extremely simple. In order to account for a possible lack of internet connection, I decided to essentially “spam” the script until I got a proper response from the server. The PHP file is navigated to using the curl utility (in quiet mode, so that I don’t notice any spam whatsoever).

Again, nothing too hefty at all. All of the meat is handled by the curl utility.


time=`date +%s`

response=`curl -s# ${url}?system=${operatingsystem}&time=${time}&action=${action}
while [[ ${response} != 1 ]]; do
        response=`curl -s# ${url}system=${operatingsystem}&time=${time}&action=${action}
        if [[ ${resonse} == 0 ]]; then
                exit 0
        printf ${response}
exit 0


On Windows, it is essentially the same story. In order to recover from a lack of internet connection, I decided to plop the whole thing in a while loop so that it ran until it found a response. Not sure whether or not having a broken pipe would throw an exception, I also wrapped the whole thing in a try/catch that when caught simply looped back to the beginning of the method.

All of this was implemented in C#.Net and uses a WebClient to do the heavylifting and post the data to the server. The code is almost identical to that of the BASH script:

class Program
 static void Main(string[] args)
 string action = "logout";
 WebClient wc = new WebClient();
 string time = ConvertToUnixTimestamp(DateTime.Now).ToString();
 string resp = wc.DownloadString(url + "?system=windows&time=" + time + "&action=" + action);
 while (int.Parse(resp) != 1)
 resp = wc.DownloadString(url + "?system=windows&time=" + time + "&action=" + action);
 catch (Exception e)

public static double ConvertToUnixTimestamp(DateTime date)
 DateTime origin = new DateTime(1970, 1, 1, 0, 0, 0, 0);
 TimeSpan diff = date.ToUniversalTime() - origin;
 return Math.Floor(diff.TotalSeconds);

Getting the Scripts To Run

Getting the scripts to run at the right time was probably the most challenging part. I didn’t have to worry about running the scripts many, many times since the PHP servlet took care of any situations that didn’t make sense (If we logged in twice, per se); however, automatically executing the scripts when the computer is turned on or off is a daunting task.


In order to get this to work on Linux, I called the script from my /etc/rc.local file, which launched the script on the computer’s start with no problems whatsoever.

Shutdown was a different story, however. Since during shutdown the network adapter is shut down very early, I had to make sure that my script would run before anything else in the shutdown process. I learned that in order to get something to run on shutdown, there is a small process to go through:

1) Copy your script to /etc/init.d
2) Make a symlink of it in /etc/rc0.d
3) Make a symlink of it in /etc/rc6.d

Then, within rc?.d, the symlinks are actually executed in ASCIIbetical order, so in order to make sure that my scripts executed first, I made sure to insert ‘A01’ at the beginning of the symlink names. I think that did the trick, since everything works properly!


Getting things to automatically start in Windows is a bit trickier. There were some suggestions on the internet to use the Group Policies Editor in order to add my programs as Startup/Shutdown scripts; however, these did not work for me for whatever reason.

To solve the startup issue, I made a shortcut to my script’s executable and plopped it into the startup folder in order to make sure that it got launched when Windows started.

Shutdown, however, is a bit more complicated. Since there is no way that  I know of to control Windows shutdown process, I decided to make a simple wrapper script for shutting down my computer. Instead of simply shutting it down, it calls my OSTracker script and then tells the computer to shut down. A easy, two line, batch script. The only caveat? It’s sitting on my desktop and I need to be sure to double click it whenever I need to shutdown my Windows machine. Shouldn’t be too hard to remember!

The Display

Now comes the fun part. How do I display this information to the public? I decided to go with a line graph. Although it’s probably not the best choice, it looks cool, and with a ‘1’ representing logged in and a ‘0’ representing logged off, it’s definitely easy to decipher a line graph like such.

In order to implement the graph, I used Chart.js. As a bonus, Chart comes with some pretty cool animations, so it made my page look just a tad nicer than I had originally intended.

Basically, the JavaScript page makes use of regular expressions to find the operating system, time, and action taken on each line of the statistics file. Nothing too interesting, so I’ll just skip the ramble.

The Product

As you could probably deduce if you actually read any of my rambling, this system is extremely hacked together. Nothing was really planned out and it took me about 6 hours to complete. However, this is my first spur-of-the-moment project in quite some time. It feels great.

Here are the results: https://brandonio21.com/OSTrackerStats/