Berkeley Mono Variable (TX-02) in Ghostty

Inspired by Michael Bommarito’s post, I’m just dropping some quick notes on getting Berkeley Mono Variable (TX-02) to work in Ghostty. Specifically, Berkeley Mono 2.002, released on 2024-12-31, running in Ghostty 1.1.3-arch1. Using the variable version of the font is highly convenient: it is very fast to change styles and tweak things until it is exactly how you like it, without having to iterate with installing static fonts.

I suggest you read his post first for lots of nice context on fonts and their features.

Then, the key bit of information I needed to get this working was the following. TX-02, the updated version of Berkeley Mono, has different OpenType features than the original. There is no documentation I could find on exactly what they mean, but via some trial and error, I’ve landed on the following config.

font-family = "Berkeley Mono Variable"

# Font width (60 to 100)
#  60 = UltraCondensed
#  70 = ExtraCondensed
#  80 = Condensed
#  90 = SemiCondensed
# 100 = Normal
font-variation = wdth=90

# Font weight (100 to 900)
# 100 = Thin
# 200 = ExtraLight
# 300 = Light
# 350 = SemiLight
# 400 = Regular
# 500 = Medium
# 600 = SemiBold
# 700 = Bold
# 800 = ExtraBold
# 900 = Black
font-variation = wght=400

# Font slant (0 to -16)
#   0 = Regular
# -16 = Oblique
font-variation = slnt=0

# otfinfo -f ~/.local/share/fonts/Berkeley\ Mono\ Variable.otf
# aalt    Access All Alternates
# calt    Contextual Alternates
# ccmp    Glyph Composition/Decomposition
# mark    Mark Positioning
# mkmk    Mark to Mark Positioning
# salt    Stylistic Alternates
# ss01    Stylistic Set 1 <- slashed 0
# ss02    Stylistic Set 2 <- dotted 0
# ss03    Stylistic Set 3 <- gap 0
# ss04    Stylistic Set 4 <- slashed 0, slash 7
# ss05    Stylistic Set 5 <- dotted 0, slash 7
# ss06    Stylistic Set 6 <- gap 0, slash 7
font-feature = +calt
font-feature = +ss02

font-size = 13
# Personal preference
adjust-cell-height = -2%

Specifically, I found that aalt and salt appear to change what the stylistic sets do (to different things than my comments). ccmp, mark, and mkmk don’t do anything that I noticed. So, effectively, it seems to me that the only two features you actually care about are your font-variation settings, and then whether you want ligatures with calt, and what style of 0/7 you want via stylistic sets.

Another tip: if you have static versions of Berkeley Mono installed, I noticed that that sometimes breaks Ghostty from loading Berkeley Mono Variable. I’m unsure why, but I was able to resolve it by removing the static fonts, configuring things, and then putting them back.