## Keep Crashing Daemons Running on FreeBSD

UPDATE 1 [2019/05/11]: Thanks to @mirrorbox’s suggestion, I refactored the script to use service status instead of ps aux | grep which makes the script even more simple. As a result, the syntax has changed. Since I keep the article untouched, for the updated code visit either the GitHub or GitLab repositories. The new syntax is as follows:

# Syntax
$/path/to/daemon-keeper.sh Correct usage: daemon-keeper.sh -d {daemon} -e {extra daemon to (re)start} [-e {another extra daemon to (re)start}] [... even more -e and extra daemons to (re)start] # Example$ /path/to/daemon-keeper.sh -d "clamav-clamd" -e "dovecot"

# Crontab
$sudo -u root -g wheel crontab -l # At every minute * * * * * /usr/local/cron-scripts/daemon-keeper.sh -d "clamav-clamd" -e "dovecot" UPDATE 2 [2019/05/11]: Another thanks to @mirrorbox for mentioning sysutils/daemontools which seems a proven solution for restarting a crashing daemon. It makes this hack redundant. Daemontools is a small set of /very/ useful utilities, from Dan Bernstein. They are mainly used for controlling processes, and maintaining logfiles. WWW: http://cr.yp.to/daemontools.html  UPDATE 3 [2019/05/11]: Thanks to @dlangille for mentioning sysutils/py-supervisor, which seems to be a viable alternative to sysutils/daemontools. Supervisor is a client/server system that allows its users to monitor and control a number of processes on UNIX-like operating systems. It shares some of the same goals of programs like launchd, daemontools, and runit. Unlike some of these programs, it is not meant to be run as a substitute for init as "process id 1". Instead it is meant to be used to control processes related to a project or a customer, and is meant to start like any other program at boot time. WWW: http://supervisord.org/  UPDATE 4 [2019/05/13]: Thanks to @olevole for mentioning sysutils/fsc. It is minimalistic, dependency free and designed for FreeBSD: The FreeBSD Services Control software provides service monitoring, restarting, and event logging for FreeBSD servers. The core functionality is a daemon (fscd) which is interfaced with using fscadm. See manual pages for more information.  UPDATE 5 [2019/05/13]: Thanks to @jcigar for bringing daemon(8) to my attention, which is available in the base system and it seems perfectly capable of doing what I was going to achieve in my script and more. Amidst all the chaos in the current stage of my life, I don’t know exactly what got into me that I thought it was a good idea to perform a major upgrade on a production FreeBSD server from 11.2-RELENG to 12.0-RELENG, when I even did not have enough time to go through /usr/src/UPDATING thoroughly or consult the Release Notes or the Errata properly; let alone hitting some esoteric changes which technically crippled my mail server, when I realized it has been over a week that I haven’t been receiving any new emails. At first, I did not take it seriously. Just rebooted the server and prayed to the gods that it won’t happen again. It was a quick fix and it seemed to work. Until after a few days, I noticed that it happened again. This time I prayed to the gods even harder - both the old ones and the new ones ¯\_(ツ)_/¯ - and rebuilt every installed ports all over again in order to make sure I did not miss anything. I went for another reboot and, ops! There it was again laughing at me. Thus, losing all faith in the gods, which led me to take up responsibility and investigate more on this issue or ask the experts on the FreeBSD forums. After messing around with it, it turned out that the culprit is clamav-clamd service crashing without any apparent reason at first. I fired up htop after restarting clamav-clamd and figured even at idle times it devours around ~ 30% of the available memory. According to this Stack Exchange answer: ClamAV holds the search strings using the classic string (Boyer Moore) and regular expression (Aho Corasick) algorithms. Being algorithms from the 1970s they are extemely memory efficient. The problem is the huge number of virus signatures. This leads to the algorithms’ datastructures growing quite large. You can’t send those datastructures to swap, as there are no parts of the algorithms’ datastructures accessed less often than other parts. If you do force pages of them to swap disk, then they’ll be referenced moments later and just swap straight back in. (Technically we say “the random access of the datastructure forces the entire datastructure to be in the process’s working set of memory”.) The datastructures are needed if you are scanning from the command line or scanning from a daemon. You can’t use just a portion of the virus signatures, as you don’t get to choose which viruses you will be sent, and thus can’t tell which signatures you will need. I guess due to some arcane changes in 12.0-RELEASE, FreeBSD kills memory hogs such as clamav-clamd daemon (don’t take my word for it; it is just a poor man’s guess). I even tried to lower the memory usage without much of a success. At the end, there were not too many choices or workarounds around the corner: A. Pray to the gods that it go away by itself, which I deemed impractical B. Put aside laziness, and replace security/clamsmtp with security/amavisd-new in order to be able to run ClamAV on-demand which has its own pros and cons C. Write a quick POSIX-shell script to scan for a running clamav-clamd process using ps aux | grep clamd, set it up as a cron job with X-minute(s) interval, and then start the server if it cannot be found running, and be done with it for the time being. For the sake of slothfulness, I opted to go with option C. As a consequence, I came up with a generic simple script that is able to not only monitor and restart the clamav-clamd service but also is able to keep any other crashing services running on FreeBSD. [Read More...] ## My Reddit Wallpaper Downloader Script Update [2019/05/08]: Many people have been asking for the wallpaper in the above screenshot. It is from System Failure II, oil on canvas, 31x43” on r/Art. Well, I am really fascinated by Reddit art and genuine creative ideas such as Scrolller which was made possible thanks to gazillions of art pieces scattered throughout various art subreddits. I am also fascinated by Unix philosophy and have been a *nix enthusiast for as long as I can remember. In addition to all this, the discovery of r/unixporn - realizing I am not the only one who cares about aesthetics of their Unix box - was a huge blow for me; to the point that studying the GitHub dotfiles posted along the screenshots on r/unixporn by fellow nix-enthusiast redditors felt like a day to day hubby for me. All the while, I had a successful experiment with writing a complex piece of real-world software in pure Bash with an amazingly wide range of features for around 3.5K lines of code. The real excitement came when it made to the official FreeBSD Ports Tree. In spite of the fact that many people find Bash syntax annoyingly ugly and unmaintainable and often wonder why do people still write shell scripts by asking it on Quora, since MS-DOS 6.22 era, I did develop a certain love–hate relationship with shell scripting languages such as Batch Files, Bash, etc. Thus, still I do automate almost everything with these ancient technologies. So, here is my fully-configurable wallpaper changer software written in bash which automagically fetches and display wallpapers from your favorite subs. It has been powering and brightening up my i3wm setup for the past eight months which led me to the conclusion that it deserves a proper introduction. [Read More...] ## How to Run Multiplayer Call of Duty 4: Modern Warfare (Promod LIVE) using Wine on GNU/Linux Well, I haven’t played a multiplayer game in ages until recently, when my cool boss announced regular playtimes for all the employees in our company as a group activity in order to put the fun back into work. Since I’m a die-hard COD4 fan and I used to play Promod LIVE heavily with colleagues and friends, I proposed Call of Duty 4: Promod LIVE 220 which happened to be favored by everybody; except there was one issue: everyone uses Microsoft Windows while I’m developing UE4 games on a single-boot Funtoo Linux system. Naturally, my first attempt was running it inside a Windows 7 virtual machine under VMWare Workstation for Linux which supports up to Direct3D 10 (the exact API used by COD4). Sadly, the experience was very poor and painful with lots of unbearable stuttering on my decent hardware. Thus, the last resort was running it under Wine, which I used to happily run many Windows applications and games under it for many years. Though, throughout those years I replaced almost every Windows application with an equivalent or an alternative Linux application until I gradually stopped using it. In the meanwhile, I also distanced myself from traditional desktop environments such as GNOME, KDE, Xfce, and LXDE, while experimenting with various window managers specially i3wm, which caught my attention for many good reasons. So, in the end I made up my mind and alienated myself from desktop environments once and for all. Running a fully-fledged game engine such as Unreal Engine 4, I expected COD4, Wine, and i3 combination to work fine out of the box as it would under any other DE. Well, it turned out that I was too simple-minded about running a fullscreen game such as COD4 under Wine/i3wm. Hopefully, as the Wine FAQ states the workaround is super easy. Here is the full guide on running COD4 v1.7 with Promod LIVE 2.20 on GNU/Linux. [Read More...] ## Migrating From Hexo To Hugo Hexo was so perfect and fast that I thought I will live with it happily ever after forever. Shortly, after I migrated this blog from Octopress 2.x to Hexo, I came across Hugo static generator with support for blogging. The idea of having a blazingly fast static generator written in a compiled native language seemed intriguing to me. I tried to migrate my blog to Hugo soon after multiple times which led to failure every single time due to lack of a few features in Hugo. Fast-forward, I played around with Gutenburg (written in Rust) a few month back. I found it to be an awesome project. Not only, every feature put together thoughtfully, but also the developer is very very responsive and welcomes new ideas and contributions warmly. Nonetheless, it’s still young and immature. So, it failed me too. I came back to check out Hugo once more last week and to my surprise, I found it really stable and production ready with tons of features and themes. So, here is my new blog ported over to the mighty Hugo. P.S. Although Hugo satisfies all my current needs, I’m more interested in Rust projects than the Go ones since I’m playing around with Rust as an alternative to Modern C++ these days. So, I’ll keep an eye on Gutenberg; who knows another port might be underway :) ## Discourse as a Blog Comment Service on FreeBSD without Docker Update 1 [2016/09/30]: A section has been added to the end of the article for dealing with major FreeBSD upgrades. Update 2 [2016/09/30]: A section has been added to the end of the article for upgrading current installation of Discourse to newer versions. Update 3 [2016/09/30]: A section has been added to the end of the article for installing Discourse under Ruby version managers which is required for dealing with newer versions of Discourse since the current system-wide version of Ruby on FreeBSD is 2.2.5p319. Update 4 [2016/10/06]: I decided to get rid of Discourse on this blog for various reasons including negative feedback from my readers, performance issues, being a memory hog and not so easy on memory, difficult maintenance, dealing with building Ruby Gems which is a tedious task in case they fail to build and a bug that duplicates my posts and creates a new thread for each post which means it won’t show previous comments. Last but not least, in my estimation it’s too heavy for such a small task such as a comment system. As a result, this guide won’t be maintained anymore. Well, when it comes to blog comment hosting services for static blogs, you will have a plethora of options such as SolidOpinion, Disqus, Livefyre, Google+ or Facebook comments, and many more. Unfortunately, such services has never been an option for me and I resisted them like forever. Yes, I’ve got one million reasons to believe and do so which demands another post of its own. So, I’ll avoid that argument for now. This left me with two choices: • Operate my blogs without the comment section as I did for years • Running an open source self-host blog comment system such as HashOver, Isso, Juvia and talkatv Since people asked me for a way to discuss their feedback on the website, this made the former choice a no go, anymore. So, in a search for the promised commenting system, I spent hours installing and trying every single FLOSS commenting system on GitHub. And everyone of them has had a big flaw that I could not tolerate. Finally, I came to the conclusion that I’m out of luck with that. Of course, I always had the option to write my own commenting system according to my own needs. As, I did with my own blog subscription system. But, due to the lack of time that was not an option either. It happens that I randomly visit Coding Horror by Jeff Atwood the co-founder of Stack Overflow and Stack Exchange Network. I’ve always read the comments on Coding Horror but never had an urge to write a comment their. Since I’ve been desperately looking for a commenting system, this time the different look of its comment system catched my attention. Bingo! He wrote an open source discussion platform software named Discourse. Not necessarily a blog comment system, but could be used as one. It even supports the Farsi language and RTL out of the box which allows me to use it on my Farsi blog, too. In addition to that it supports multi-site which means I have to only run one instance for all my blogs. Just perfect! Despite many nice feature it provides, it has a few rough edges, too. I was able to conquer some and some couldn’t, yet. But it did not stop me from integrating it into my Hexo-based blogs after two weeks of testing it. So, there it is, from now on both this blog and my Farsi blog are discussion aware :). OK, the main issue that many people face when they want to install Discourse in a platform other than GNU/Linux, is they get hit in the face by the reading this line in the official documentation: Why do you only officially support Docker? Hosting Rails applications is complicated. Even if you already have Postgres, Redis and Ruby installed on your server, you still need to worry about running and monitoring your Sidekiq and Rails processes. Additionally, our Docker install comes bundled with a web-based GUI that makes upgrading to new versions of Discourse as easy as clicking a button. Yes, I know Ruby and Rails are crap and deploying Ruby on Rails apps are pain in the Butt. Do not worry! This was the first struggle with Discourse that I had since this blog runs on FreeBSD. And, FreeBSD support for Docker is experimental, yet. Fortunately, I used to deploy GitLab instances on FreeBSD for three years which was also RoR before I migrated to Gogs which kicks butt, anyway! That made it easy to figure out a simple way to deploy Discourse without Docker on FreeBSD. [Read More...] ## Android: Install ADB drivers for any device without OEM drivers Well, I started my Android development on a Samsung I9100 Galaxy S II. I never had any trouble getting ADB to work on Microsoft Windows since I had the drivers from Samsung which was already installed due to my previous Cyanogenmod installation process. Afterwards, I received a Nexus 7 and a bit latter a Nexus 5 which became my primary development device of choice. Google did a good job by providing ADB drivers for All Nexus devices inside the SDK or as a small separate download on Android Developers website which was very easy to install. The trouble began when my development process involved testing my applications and games on devices other than Nexus ones I had. For some manufacturers I was never able to find the drivers. Finding the correct driver for each device was a huge pain until I found a solution that became a remedy for all my troubles getting ADB to work with any Android device, even without the OEM drivers. It even became my preferred alternative to manufacturer’s provided ADB drivers for all my other devices till this day, since I hate the bloat-ware and useless crap they provide along with their drivers which is inevitable to install anyway. In the rest of this post I’m going to share my easy solution with you: [Read More...] ## Post-Processing Effects in Cocos2d-x Despite the fact that Cocos2d-x uses the OpenGL ES Shading Language v1.0 for the shaders (in order to learn more about the language, please refer to: OpenGL ES Shading Language v1.0 Spec) the engine does not provide an out-of-the-box API to apply post-processing effects to the whole game scene output at once. In this tutorial we will learn an easy way to apply multiple post-processing effects to the game scene output all at once. [Read More...] ## Delete a File With Invalid or Bad Characters in File Name on FreeBSD There once was a time when I did the following inside my home directory: $ wget "some-url" -O "output-file.mp4"

I clearly remember copying the output file name from a web page. Unfortunately, the copied text has a new line at the beginning of it and I didn’t notice that. That’s because the newline or carriage return characters are control characters and have no visual representation. Anyway, when I listed files inside my home directory I noticed a strange file name on my list:

\$ ls
?output-file.mp4