Hello nixers,

In this thread we'll talk about a topic that came up on IRC yesterday: font fallback.

Many of the popular desktop environments already come with a preset of fonts that has good support for a wide range of unicode characters.

However, what if you want more power over these, over the order in which they will fallback, or what about building your own font fallback font line.

Font fallback is software based, that means it's upon the software to handle it. Normally, software that relies on fontconfig will ask it for information regarding a name, let's say "monospace", and fontconfig will return a list of all the fonts, in order, that can support characters that are monospace. Then the software will try to draw a character by searching for it within the first font in the list, if it doesn't find it, it'll continue to the second, and so forth.

You can test that by doing:

Monospace isn't a font that exists but an alias for many fonts that can fulfill it.

If you want more info about this, I've written a bit about FcNameMatch and fc_finding_pattern here. The crux of it, is that it tries to match via properties.

So in theory, you can start with your favorite font, which you know supports the characters you use the most, and then add to the list other fonts that support lesser known characters such as emojis.

Here's a good list of unicode fonts I found, please share yours too:

• Symbola
  
• Noto Emoji
  
• Twitter Color Emoji
  
• Pan-CJK
  

But, that's for the case in which we can actually control the exact fallback order that will be taken. Otherwise, we have to rely on the fontconfig mechanism for fontfallback.
Both the ArchWiki and this article mention ways to do so. But if you dislike editing XML files via text editors, I propose using the fontweak tool instead.

Here's a screenshot of it:




So, how do you handle font fallback. Which fonts do you use? Does it display properly in your terminal and across your environment?