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UNIX philosophy, modularity and software harmony

March 1, 2022

Do One Thing and Do It Well

Today, I want to talk about a small part of UNIX philosophy. If you want a thorough summary of all the different “schools of thought” that concerns the term UNIX philosophy, I recommend the Wikipedia entry. From there, you can probably find books and articles that will explain what it is better than I will be able to.

From here onwards, I will focus on one of /g/’s most quoted component of UNIX philosophy: “Do One Thing and Do It Well”. This principle suggests that software designers and developers must strive to avoid adding “bloat” to their software, a term all suckless users abhor. To quote Doug Mcllroy (1978):

Make each program do one thing well. To do a new job, build afresh rather than complicate old programs by adding new "features".

What makes a software “bloated”, exactly? Here, “bloat” does not mean an operating system or user-space that comes with many different software installed; today’s definition of “bloat” applies on a software-design level. Of course, there are definitely overlaps, but the nuance is here to refrain elitists from saying something along the line of “Ubuntu is bloat, install Gentoo”. It’s not about Candy Crush being installed as a default program on your grandma’s computer, it’s about a self-contained software on its own.

Like many other subjective qualities, you can often find the term “bloated” predicated to any software which comes pre-packaged with too many built-in functionalities, often times derailing from its main job (even worse, it might be lacking in any true singular functionality). This symptom of a software developing bloat is appropriately termed “feature-creep”. This leads onto my first contention: software bloat is synonymous to “feature-creep”, and any other definition eventually reduces to user-preference, which is subjective.


The way a software is interactively displayed is one of its primary properties. It affects the way functionalities are carried out, such as input, output, configuration, integration with other software, along with its user friendliness. But often, the functions themselves are not gravely modified through the choice of the interactive system. But since it is part of any software, is causally related, if any, to a software’s bloat?

The straightforward answer is: such a feature is a necessary feature, therefore whatever the choice may be, it cannot be inherently bloated.

However, one might contend through observation that often times, software that comes packaged with a GUI is more bloated than a command line interface (CLI) or terminal user interface (TUI). Take Redshift, which is a utility that allows you to make your monitor warmer. Whether or not it is scientifically proven to help your eyes is another matter, some like me just find such a screen more comfortable to look at. Now, Redshift can be configured through a text file, and run via the command line or as a daemon, a systemd unit for example. But there also exists GUI wrappers and similar options that come with a GUI. Are they inherently more bloated because I can now drag sliders to adjust the temperature of the screen? No. What it harms ever so slightly is software harmony (I will get onto this), since I can use a text editor to edit configuration files of any software, unifying my user experience. I don’t want 3 different software with 3 different GUI libraries that obfuscate the concept of tweaking options, which on its own does not need a GUI. However, displaying a representation of the colours, one could say, is more easily done with a GUI. Effectively, you want to stick to the best option for your software (so that it does its one thing well). Otherwise, it is purely a matter of preference. A rough guideline is that text-based and static software for CLI, and dynamic, pictorial ones for GUI).

Let’s take the concept of a music player. Its job is to perform tasks like playing and changing track, display metadata, list your library or a playlist. With a CLI, one can design it so that $ music_player /path/to/track.ext will play a track, and through built-in commands, one can see what is being played plus other things, even though it will not be dynamic. This is still a music player, despite it being worlds different from foobar2000 or Winamp or iTunes. If we go with a TUI or GUI, and the music player does the same thing (same = functionally, and a function is conceptual, not visual), it would also have the same level of features, and hence the same level of bloat. So if you’re one of those people, please don’t call GUIs bloat because you like to do everything through your terminal. Again, it is preference. A GUI music player can definitely “do one thing and do it well”.

TL;DR: Choosing how you want your software interface to be delivered does not, and should not affect its inherent level of bloat, as long as the functions are carried out in the same way.

This same argument applies to the choice of programming language as well. While choosing a low level and highly optimised language might introduce less latency, this does not have anything to do with software bloat. The language itself might be bloated, but this does not transfer onto the software it compiles. The language is a tool, not the feature.

The only way to introduce bloat to a music player would be add a Jenga tower chock full of features. Features which deviate from tasks listed above. Here’s an example, I’m using ncmpcpp right now, which is a TUI mpd client, do I ever use its tag editor? No. Musicbrainz Picard can do that. How about the clock? Absolutely not, I have a watch. The visualiser? Not something I look at while working or studying. Is ncmpcpp bloated then? Yes. Despite that, I like its TUI, and it’s a trade-off I’m willing to make insofar as time is concerned (more on this below). It is one of the most popular clients and that’s how I found it. If I can reduce the installed size of about 2.6 MiB by switching to something smaller to avoid the features I don’t need, I am obliged to in adherence to the principle.

Plugins and scripts

“My music player is too basic! How do make it more attractive?! Or even better, how do I get others to contribute to it without it getting bloated?”

The solution is to add a very special feature to your software, a plug-in framework. Now, you can add to your software in the form of scripts or patches. Doing so will introduce modularity, which is the ability to separate a system’s component in order to recombine and add variety and uniqueness to how a user might choose to use it. One can add modularity easily by adding an application programming interface (API) or a interprocess communication (IPC) system. This way, no one really needs to read the entire source code in order to expand the functionality.

Plug-ins, extensions, add-ons, add-ins, however you wish to call them, inherently follow UNIX philosophy. The modular nature of software is what the principle “Do One Thing and Do It Well” alludes to. Not only does it help the developer focus on individual parts of a software to ensure it is optimised and bug-free, it is also user-friendly because this results in a highly customisable experience. Good examples include vim, mpv, and any suckless software. I want to particularly highlight i3, which is a feature-packed window manager. Even though it does quite few things, they all do what window managers do. The only exception, i.e. my only complain is arguably i3bar (a status bar), which could be its own package like i3status (allows communication with the system to display the status). Despite that, i3 has a IPC framework in Python that allows scripts to extend its power.

The simplest expansion of functionality is interface customisation. Making a framework to allow changing the theme of your software is one example. Instead of hard-coding a light and dark theme with your own predefined colours, it would be better to allow users to pick from a set of themes and ultimately edit and add in their own custom themes. On Linux, this applies to only TUI and CLI, GUI program normally are written in GTK or QT, which means they follow the theme you set your system to display globally. Nevertheless, the option is technically still there in form of tweaking GTK and QT.

To advance higher, one could introduce a plug-in framework which allows scripts to be written in any popular languages such as Lua, Python, Perl, etc. For a music player, this might be a tag editor, a visualiser, a clock, etc. Weechat, an IRC chat client, is a good example of how plug-ins are implemented. Although most of them are visual enhancements, some of them add in new functionalities that improve on quality of life.

TL;DR: Plug-ins are friends, not foes, when it comes to UNIX philosophy. Instead of force-feeding users to install 100% of the features you plan, they can pick and choose their own suite of functionalities. This is modularity and it is a good thing in software design. Thus, it is always better to make a framework that allow external scripts to expand a software's functionalities, than to include every feature.

Software utopia and why harmony is so difficult to achieve (a more personal passage)

“I follow UNIX philosophy to write my software, now what? I have to make sure it works with other software and utilities too. This is too much work.”

Well, don’t take advice from me, I’m no expert. But as a power user, I have spent more than half my life on the computer, and I share some sentiment when it comes to integration with other tools people wrote. It is a lot easier to write cohesive and perhaps harmonious software with a group of people with strict guidelines, but this is not the case with non-Big-Tech, ‘‘non-pozzed’’ software; small developers often work alone or with a small list of contributors. It is a lot more work to keep a clean code base for open sourcing, write guidelines for contributing, while at the same time adding modularity to your software.

Here’s a secret: most users won’t care about bloat. I’ve been to both parties. I used to make sure almost every I use is terminal-based. I love curses programs and CLI alternatives. But I slowly notice the downside of it; when something seems bloated, there is the tendency to purge it and look for a replacement. This is tiring. I want a solution that “just works”.

On my path to reduce bloat, I realise it’s not easy to fully compartmentalise and isolate everything. Communication apps and game launchers are a nightmare. To this day, I still can’t get PDF thumbnailers to work in PCmanFM without having to install the whole Evince package even though I use Zathura. If you’ve gone through something similar to this, you might’ve entertained the thought that it’s actually easier to go with bigger software that, you know it, contains a high dosage of bloat, for the sake of less headache. That’s what the majority defaults to, besides just using what comes installed on their system. The fact is, because most users won’t care about bloat, they will almost always pick it, out of convenience and lack of interest for good software. Companies will pay money for old, propriety software that are badly written and not well-maintained because they think paying for software will result in better products. Depends on how you define “better” when it comes to software, this is often not the case.

The downsides of bloated software that might not be causally related, but definitely correlated are what you might expect. Things like more overhead and lack of optimisation due to bigger codebase, a big backlog of bugs to fix, data collection and telemetry, lack of user customisation and companies that don’t listen to their users but only their investors, feature-creeping, constant UI overhaul to attract more and more users in order to make a profit in monetising collected telemetry. On the other hand, software that do follow UNIX philosophy and stay this way often come open source and free (as in beer AND speech). Many software that don’t do this are closed source, absolutely propriety, free (as in beer AND not speech). Again, most people will not care and they will buy into this.

In other news, if you share my practices and beliefs, don’t let the slight overlapping functionalities of your suite of applications get to you. If it’s the difference of about 2 MiB, it’s still a world of difference compared to a monolithic software that does everything and do them poorly, consumes > 1 GB of RAM and is probably written in Electron.

We end by returning to the music player, now in the context of harmony. A scrobbling (logging tracks and storing it in a third-party service) feature should not be included in a music player. Because one will now have to deal with third-party service’s API, then handle authentication and token storing, and also upload it to the internet, etc.. Within UNIX philosophy, this is a red flag, you are not writing a scrobbling software, you are outputting music files.

It’s not lazy to let the music player be detected by something like MPRIS, and let someone else’s software pick the metadata up and scrobble the tracks (like rescrobbled). Because their software focuses on this function alone, they will do a better job than the music player’s. Instead of excluding the part of the user base that obsessively scrobbles, the developer can instead recommend a software which works well and is tested with their music player. This will help increase exposure of the FOSS community, and pass on the legacy of decades-old philosophy.