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How to choose colors for your CLI applications (2023)
- j4cobgarby 8mo agoUse only default (white/black), red for bad, green for good. If you need more than that, like vim or whatever, then maybe a 'fullscreen' TUI is better, with a specified background and foreground. For CLI tools, I'm not sure if I prefer more colours. The CSS to make the terminals look like iTerm was smooth, to the point I read them as screenshots.
- busterarm 8mo ago> red for bad, green for good 8% of men of Northern European descent (and 0.4% of women) are red-green colorblind. That'd be a terrible choice. Use blue-orange, blue-red, or purple-green.
- makapuf 8mo agoMore importantly, dont use color as sole source of information. Strikethrough, emoji or ok / bad can also be used.
- xenophonf 8mo agoEmojis aren't 7-bit clean. They're hard to type. They don't mean things the same way words do. `foo | grep -i error` communicates intent better than `foo | grep :-/` or whatever goofy hieroglyph someone chose instead of, like, a word with clearly defined meaning.
- craftkiller 8mo ago> They're hard to type I'd like to recommend rofimoji. I have it bound to a hotkey, so whenever I want to type an emoji, I just hit that hotkey and then a window pops up with my most recent emoji already visible at the top. Then I start typing in words that describe the emoji that I want like "crying" and it filters the list. Finally I select one and it pastes it into whatever text box I had selected before I hit the hotkey. My only complaint is I wish it worked for all unicode codepoints instead of just the emoji.
- makapuf 8mo agoYes that's why I also mentioned text labels. (strikethrough ansi codes aren't also fun to type). Besides, where are you needing 7but clean data ? Isn't that a narrow use case ?
- xenophonf 8mo ago> narrow use case? It's the robustness principle. "Be conservative in what you do, be liberal in what you accept from others." A CLI author shouldn't assume support for UTF-8.
- Lammy 8mo ago> They're hard to type. Globe key + E on Mac, Windows key + period on Windows, Ctrl + period on GNOME, Super key + period on KDE, yada yada.
- wredcoll 8mo agoIn my experience with live codebases, "error" or "warning" rarely mean the same thing to the same person, but admittedly you're much more likely to guess that they're in use as opposed to crying-green-clown emoji
- makapuf 8mo agook in that context use error or ok, just dont use color as ~10% of ppl have an issue with seeing colors perfectly (that includes people with epaper displays)
- skydhash 8mo agoRed/green is semantic in these cases. They’re user configurable in almost all terminals, so there’s no real accessibility issue. I tend to associate blue with decorative accent, yellow with info/warning text, and cyan and magenta for really fancy stuff.
- tczMUFlmoNk 8mo agoRed/green has no inherent semantics. It has the semantics that you assign it. If you choose to assign it meaning that disenfranchises 8% of men using your system, that's your choice, but it is not a good one.
- skydhash 8mo agoCultural semantics (diff tools, build tools,…: green/addition/ok, red/removal/error). And people with color blindness can alter the colors to something they can differentiate. And in the ansi sequences, they are actually numbers.
- mrob 8mo agoThe standard terminal palette is only 16 colors. Even if you compress them all into the green-to-blue color range, it's still possible to distinguish all 16. The user can change "red" and "green" to whatever they like in the terminal preferences and then every 16-color app will be accessible with no additional effort from anybody.
- Etheryte 8mo agoThis approach is worse. Use red and green like everyone else and the user can choose their terminal color palette to differentiate in a way that works for them. Then it works the same across all commands. If you're the odd one out, you're adding more mental overhead for the user, not less.
- account42 8mo agoYou are ignoring that most people already have a cultural understanding of the colors red and green. Changes done for accessibility should never making things worse for the average user.
- BeetleB 8mo agoHard disagree on the red/green. Use whatever you think appropriate and make it user configurable.
- mrob 8mo agoIt's a CLI app, it's already configurable. Every good terminal emulator lets you set custom palettes.
- kps 8mo ago>Every good terminal emulator lets you set custom palettes Not differently for each program's output.
- mrob 8mo agoWhich is a good reason to stick with the de-facto standard of red for bad and green for good.
- sceptic123 8mo agounless you're colour blind
- mrob 8mo agoIf you're color blind, you change the palette in your terminal emulator so "red" and "green" become different colors you can distinguish. It even works for rarer forms of color blindness. This works best when people follow the de-facto standard.
- skydhash 8mo agoRed here does not mean #ff0000. it means color 1. in the 4 bit colors palette
- hulitu 8mo ago
- red_admiral 8mo agoEh, LS_COLORS is sometimes useful once the meanings are in your subconscious.
- fassssst 8mo agoColor is cultural. Red is associated with good in China
- altcognito 8mo agoContext here matters, red finds its way into Chinese forbidden or warning signs quite often.
- the_gipsy 8mo ago[flagged]
- Arch-TK 8mo agoMost things work fine with black on white terminals. If your software does something dumb when my theme switches to black on white during the day then I am just going to avoid using it...
- taswellian 8mo agoIt's easier to see dark text on a light background for people with astigmatism.
- JoshTriplett 8mo agoOr for people working outside. Or for people using an e-ink display.
- strogonoff 8mo agoAccommodating terminal colour schemes, however crazy to you they might be—white on black, black on white, dark brown on off-white Solarized-style, etc.—is basics of TUI design. Personally I alternate between light on dark and dark on light (the latter sometimes together with OS-wide colour inversion feature).
- skydhash 8mo ago> People who use white themed terminals are psychopaths anyway Dark background is hell for anyone with astigmatism. It’s fine with 80x24 (vga text mode), but for anything higher feels like light needles on the retina. With astigmatism everything that is bright and small is duplicated, which means small characters is very difficult to read.
- deleted 8mo ago[deleted]
- xenophonf 8mo agoI really wish you wouldn't. All the rinky dink colors and animations screw with the CLI output when you don't correctly detect whether the user's running the app interactively. Keep it plain text. Regular, old, boring output is good.
- skydhash 8mo agoI dislike when devs only try to detect if it’s a tty, then enable all their gimmicks without even providing a flag. Not everything is xterm-256color.
- kps 8mo agoAnd not everything that calls itself xterm-256color is actually xterm compatible *cough* GNOME *cough*.
- bitwize 8mo agoXterm is actually a terminal emulator, and has to pass a suite of conformance tests that actually check its emulation of DEC VT series terminals. Most of its successors are more like "shitty xterm emulators" whose conformance tests are "do my favorite mOdErN CLI apps work".
- davidw 8mo agoYeah. "The only winning move is not to play".
- bitwize 8mo agoI agree. So many TUIs from webshit devs don't even bother to call isatty, let alone check terminfo to see if ANSI escape codes are even valid for this terminal. But modern open source subscribes to Mao's Continuous Revolution Theory. Calls for some measure of stability and sanity are usually dismissed with some form of the argument "awwww, is poor diddums afwaid of a widdle change?" Or in this case, "still using vi on your ADM3A, old timer? Our software is not for you."
- sroussey 8mo agoThis is true for the console in dev tools as well. Problem there is you can’t change css so at the moment the systems color preference changes thing will look bad. Important considerations for custom formatters.
- sroussey 8mo agoHere is a screenshot for my personal example: https://github.com/workglow-dev/workglow/blob/main/docs/developers/img/console.png https://github.com/workglow-dev/workglow/blob/main/docs/deve... Play with it here using dev tools (you can ignore the website itself): https://workglow-web.netlify.app/ https://workglow-web.netlify.app/ Docs including útil for checking dark mode: https://github.com/workglow-dev/workglow/tree/main/packages/debug https://github.com/workglow-dev/workglow/tree/main/packages/...
- seanwilson 8mo agoIf the goal of the post is to pick terminal colors that contrast on both white/light and black/dark backgrounds, it means you're stuck with midtone colors (between light and dark). This is really limiting for color choice (there's no such thing as "dark yellow" for example), and lowers the maximum contrast you can have for text because you get the best contrast when one color is dark and the other is light. Ideally, instead of the CLI app switching to "bright green", it would pick a "bright contrasting green". So if the terminal background was dark, it would pick bright green, and for light background it would pick a darker green. There isn't CLI app implementations for this? This is similar to how you'd implement dark mode in a web app.
- alt187 8mo agoThat's called `\e[0;92m`, aka the ANSI terminal espace sequence for bright green. You have 15 others, that will be displayed however the terminal's user wants. They're already available in most terminal color libraries, too.
- account42 8mo ago> Ideally, instead of the CLI app switching to "bright green", it would pick a "bright contrasting green". So if the terminal background was dark, it would pick bright green, and for light background it would pick a darker green. There isn't CLI app implementations for this? This is similar to how you'd implement dark mode in a web app. The responsibility for this lies with the color scheme not the terminal program.
- JoshTriplett 8mo agoCLI apps can detect the background color of the terminal, and determine contrasting colors accordingly.
- takluyver 8mo agoThey can? Is this a recent thing? I remember wanting to detect the background colour years ago, and not finding any way to do it.
- red_admiral 8mo agoThere's an ever more basic rule: don't just make your text white (ANSI 37m) because you assume the terminal will have a dark background. Even white-on-black (37;40m), while usually readable, can stand out the wrong way if you assume that everyone is using dark mode.
- account42 8mo agoIMO if your terminal theme does not provide high contrast for "white" text on the default or "black" backgrounds, that's for you to fix. If you want a light terminal then change the color scheme to map "black" to a bright color and "white" to a dark color while making sure that other colors have good contrast to your "black". Don't just change the default foreground and background color and expect every single color using program to fix your mess.
- bitwize 8mo agoIt's 2026, and app developers are solely responsible for not causing eyehurt, even if their users insist on using the Hotdog Stand theme.
- keepamovin 8mo agoCan you work this into an AGENTS.md ? Just so happen to be working on multiple TUI at the moment: text-based modern web browser, VPS rental console, agentic coding wrapper. Colors, have been a perpetual nightmare.
- alias_neo 8mo agoI recently spent several evenings re-working all of my colours across all of my computers and screens; terminals, IDEs, etc. Ultimately, despite using the same tools, and always dark mode, across all of my machines, the setup for each was different. I think it's safe to set a standard colour-set so that it's immediately usable, but beyond that, a user should be customising to their requirements. Perception differs among people; many of the colours OP listed as unreadable, were barely an issue, bright yellow being the only one I could unequivocally agree on. Perhaps display type, configuration and colour calibration is an important factor, as well as individual perception, ambient conditions, brightness levels, contrast, and perhaps even more variables have a significant effect. I've also learned, since adding an OLED Monitor to my desk alongside the IPS ones, that it's possible to have too much contrast; brightly coloured text alongside pixels that are literally off can be just as problematic to read at times, as low-contrast.
- maximgeorge 8mo ago[dead]
- layer8 8mo agoAs long as CLI programs stick to the 8 or 16 standard colors and refrain from setting background colors (inverse mode is fine), as well as from explicitly setting white or black as text color, everyone can reasonably configure their terminal colors so that everything is readable. When going beyond that, the colors really need to be configurable on the application.
- JohnLeitch 8mo ago> refrain from setting background colors That's the thing though, setting bg color opens up a lot of options, and constraining to invert is not sufficient in my opinion.
- Joker_vD 8mo ago> constraining to invert is not sufficient in my opinion Eh. Doing green/red text color with default background, maybe inverted works amazing for me. In fact, I'd say that every sensible colour scheme for a terminal should have as the default foreground/background colours something that is more or less contrasting against every other explicitly named colour, including black and white (I personally have #212121 on #EEEEEE).
- layer8 8mo agoThat’s fine, but please make the colors configurable then. For example like Mutt does: http://www.mutt.org/doc/manual/#color http://www.mutt.org/doc/manual/#color
- reactordev 8mo agoSticking to the \x1b[4X background color is probably safe as that can be tweaked by terminal color palettes. It’s when you use the 256 or RGB \x1b codes that it becomes an issue. Ok for foreground.
- Arch-TK 8mo agoConfigurable within the application... at runtime. I want to be able to switch existing terminals with existing applications between themes.
- jammcq 8mo agoI'm a bit color blind and it might be quite common to show errors in red but when the background is black, I can't see it at all.
- bradrn 8mo agoNeither can I. Luckily tweaking the colours can make it somewhat readable. (Sometimes…)
- s_dev 8mo agoColourful terminals are so useful. I have mine colour coded according to the working directory depending on the project. So I can see which terminal is associated with which project even if there are twenty terminals open. The scripts are even in my servers so when I ssh in to them it changes colour as well. https://michael.mior.ca/blog/coloured-ssh-terminals/ https://michael.mior.ca/blog/coloured-ssh-terminals/
- kiddico 8mo agoVery cool. Thanks for sharing!
- thinking_cactus 8mo agoInteresting analysis, but perhaps it warrants a different conclusion: it's almost impossible to please everyone in this case. The resulting colours seem of some utility, but if you intend to make something more interesting you're probably annoy some (potentially large) group, in the case of legacy terminal coloring.
- hnsmhthrow 8mo agoI used solarized since it came out but I dropped it some years back. I don’t think I can use it for dark mode. It’s too washed out and dull compared to light mode which is what I used to use it with. I just use whatever VS Code or VIM gives me as a dark mode and it’s usually better.
- ori_b 8mo agoAs long as you respect the NO_COLOR variable, it will work for me. https://no-color.org/ https://no-color.org/
- wredcoll 8mo agoThat's a funny example. I have no issues with the idea of course but in my day to day life I'm way more likely to encounter an issue with colors being lost after sent to a pager or a log file or tee or what not
- jph 8mo agoIf you want a quick easy way to add some colors to your own shell scripts: export STDOUT_COLOR_START='[34m' export STDOUT_COLOR_STOP='[0m' export STDERR_COLOR_START='[31m' export STDERR_COLOR_STOP='[0m' In your shell script: print_stdout() { printf %s%s%s\\n "${STDOUT_COLOR_START:-}" "$*" "${STDOUT_COLOR_STOP:-}" } print_stderr() { >&2 printf %s%s%s\\n "${STDERR_COLOR_START:-}" "$*" "${STDERR_COLOR_STOP:-}" } Source: https://github.com/sixarm/unix-shell-script-kit https://github.com/sixarm/unix-shell-script-kit The source also has functions for nocolor, and detecting a dumb terminal setup that doesn't use colors, etc.
- direwolf20 8mo agoWhat is the purpose of making everything the same color?
- Rygian 8mo agostdout and stderr get different colors.
- kps 8mo ago1. That script's color check doesn't check that the output is a terminal. Also test tty -s 2. Don't hardcode escape sequences. Use (e.g.) export STDOUT_COLOR_START="`tput setaf 4`".
- jph 8mo agoYes good points both, thank you. The source code link has more explanation about color choices and my preference of POSIX compatibility. You can also see the color function that checks NO_COLOR, CLICOLOR_FORCE, TERM = "dumb", -t 1, etc. For color operands, I use raw escape codes because I aim for POSIX compatibility. If I'm working on something that needs more capabilities then I switch to a more powerful programming language e.g. python, rust, etc. As far as I understand, POSIX tput defines some terminal operands (clear, init, reset, etc.) but not color operands (setaf, setab, sgr0, etc.).
- 8mo ago
- makapuf 8mo agoI really think we should converge to semantic codes. By example Background is zero, standard is 7, positive / negative, highlight, colored1,2,3 .. with correct defaults, and let the user have a common 8 or 16 colors palette in the terminal for all textmode apps. Imagine having some kind of unified color themes in the terminal.
- tolciho 8mo agoA confused user once stopped by, they had a blank terminal, so I showed them how to select all which revealed the helpfully black on black text. These days I compile colour support out of st, or set *colorMode:false for xterm. "But you can customize the colours" is a typical response, to which one might respond that one has grown weary of pushing that particular rock, and moreover one may be busy with other things at a drag-out monitor in a server room at three in the morning that has helpfully dark blue text on a black console, or worse if some high-minded expert has gone and rubbed the backside of a unicorn everywhere so that they may improve the "legibility".
- munificent 8mo agoTangential, but I really love the design of this blog.
- alfirous 8mo agoMe too. Typography and colors are great.
- otabdeveloper4 8mo agoStep one: *always* assume a dark background.
- nateroling 8mo agoI’ve bounced off of LazyGit multiple times because I never figured out how to make it play nice with a light theme terminal. I haven’t used dark mode anything for years. I set my monitor so it’s roughly as bright, or slightly brighter than, a piece of white paper. No more flash-bangs when some website doesn’t support dark mode.
- assimpleaspossi 8mo agoBlack on white has seemed to work for centuries without issue. For general reading, throw in bold and italic and you're pretty much set. For programming, black on white is still a go to color (or lack thereof).
- lifetimerubyist 8mo agoI use the built-in TokyoNight Day theme as my light theme in GhosTTY and I think it's almost perfect. Then I use TokyoNightMoon for dark. Works great. Hard to use anything else now. If you're CLI application doesn't play nice with it (i haven't seen many) I don't use it.
- joshka 8mo agoI made the "Aardvark Blue" a while back[1] to solve some of the problems that most color schemes have. The goal of this theme is that: - colors are fairly natural - background and black are distinct - grays are naturally ordered avoiding full black - light and dark colors are distinct from each other - all colors look good on background, black, dark gray, gray, white We use this for all the screenshots on https://ratatui.rs https://ratatui.rs and https://github.com/ratatui/ratatui https://github.com/ratatui/ratatui It's available from the usual places https://iterm2colorschemes.com/ https://iterm2colorschemes.com/, https://windowsterminalthemes.dev/?theme=Aardvark%20Blue https://windowsterminalthemes.dev/?theme=Aardvark%20Blue, built in to ghostty, extension for vscode etc. [1]: https://github.com/mbadolato/iTerm2-Color-Schemes/pull/417 https://github.com/mbadolato/iTerm2-Color-Schemes/pull/417
- tasuki 8mo agoFunny thing, those are not "the usual places" I've ever heard of, and I care somewhat about color schemes. Each of us lives in our own bubble... (my bubble is not iterm2 and not windows)
- ctmnt 8mo agoWhere are some of the usual places you look?
- tasuki 8mo agoI don't usually look anywhere, but things I sometimes see pop up in various places are eg https://terminal.sexy/ https://terminal.sexy/ or https://vimcolorschemes.com/ https://vimcolorschemes.com/
- joshka 8mo agoiterm2colorschemes is a source for various other tools as it ports out to "Terminal, Konsole, PuTTY, Xresources, XRDB, Remmina, Termite, XFCE, Tilda, FreeBSD VT, Terminator, Kitty, MobaXterm, LXTerminal, Microsoft's Windows Terminal, Visual Studio, Alacritty, Ghostty, and many more." You may have used data from it without knowing about it.
- anal_reactor 8mo agoThe problem with CLI colors is that they operate on the wrong abstraction layer. Individual program shouldn't send "this text is red" but "this text signals failure" and then terminal interprets "failure" as "red". Until this change happens (never) colors in CLI will remain a hot mess.
- 0x457 8mo agoUse 8 or 16 standard colors, let me configure them via terminal emulator or give me a way to completely change color scheme. That is it. Very rarely I need per-application colors in terminal (or anywhere really).
- pimlottc 8mo agoWhat is Sorcerer here?
- loicd 8mo agoIn addition to $TERM, I wish there was a standard variable defined by terminal emulators that would contain the background color. This would let programs choose their colors accordingly, rather than try for a one-size-fits-all.