coloring_and_theming.md

Coloring and Theming in Nu

Many parts of Nushell's interface can have their color customized. All of these can be set in the config.nu configuration file. If you see the hash/hashtag/pound mark # in the config file it means the text after it is commented out.

1. table borders
2. primitive values
3. shapes (this is the command line syntax)
4. prompt
5. LS_COLORS

Table borders

Table borders are controlled by the $env.config.table.mode setting in config.nu. Here is an example:

> $env.config = {
    table: {
        mode: rounded
    }
}

Here are the current options for $env.config.table.mode:

• rounded # of course, this is the best one :)
• basic
• compact
• compact_double
• light
• thin
• with_love
• reinforced
• heavy
• none
• other

Color symbologies

---

• r - normal color red's abbreviation
• rb - normal color red's abbreviation with bold attribute
• red - normal color red
• red_bold - normal color red with bold attribute
• "#ff0000" - "#hex" format foreground color red (quotes are required)
• { fg: "#ff0000" bg: "#0000ff" attr: b } - "full #hex" format foreground red in "#hex" format with a background of blue in "#hex" format with an attribute of bold abbreviated.

attributes

---

code	meaning
l	blink
b	bold
d	dimmed
h	hidden
i	italic
r	reverse
s	strikethrough
u	underline
n	nothing
	defaults to nothing

normal colors and abbreviations

code	name
g	green
gb	green_bold
gu	green_underline
gi	green_italic
gd	green_dimmed
gr	green_reverse
gbl	green_blink
gst	green_strike
lg	light_green
lgb	light_green_bold
lgu	light_green_underline
lgi	light_green_italic
lgd	light_green_dimmed
lgr	light_green_reverse
lgbl	light_green_blink
lgst	light_green_strike
r	red
rb	red_bold
ru	red_underline
ri	red_italic
rd	red_dimmed
rr	red_reverse
rbl	red_blink
rst	red_strike
lr	light_red
lrb	light_red_bold
lru	light_red_underline
lri	light_red_italic
lrd	light_red_dimmed
lrr	light_red_reverse
lrbl	light_red_blink
lrst	light_red_strike
u	blue
ub	blue_bold
uu	blue_underline
ui	blue_italic
ud	blue_dimmed
ur	blue_reverse
ubl	blue_blink
ust	blue_strike
lu	light_blue
lub	light_blue_bold
luu	light_blue_underline
lui	light_blue_italic
lud	light_blue_dimmed
lur	light_blue_reverse
lubl	light_blue_blink
lust	light_blue_strike
b	black
bb	black_bold
bu	black_underline
bi	black_italic
bd	black_dimmed
br	black_reverse
bbl	black_blink
bst	black_strike
ligr	light_gray
ligrb	light_gray_bold
ligru	light_gray_underline
ligri	light_gray_italic
ligrd	light_gray_dimmed
ligrr	light_gray_reverse
ligrbl	light_gray_blink
ligrst	light_gray_strike
y	yellow
yb	yellow_bold
yu	yellow_underline
yi	yellow_italic
yd	yellow_dimmed
yr	yellow_reverse
ybl	yellow_blink
yst	yellow_strike
ly	light_yellow
lyb	light_yellow_bold
lyu	light_yellow_underline
lyi	light_yellow_italic
lyd	light_yellow_dimmed
lyr	light_yellow_reverse
lybl	light_yellow_blink
lyst	light_yellow_strike
p	purple
pb	purple_bold
pu	purple_underline
pi	purple_italic
pd	purple_dimmed
pr	purple_reverse
pbl	purple_blink
pst	purple_strike
lp	light_purple
lpb	light_purple_bold
lpu	light_purple_underline
lpi	light_purple_italic
lpd	light_purple_dimmed
lpr	light_purple_reverse
lpbl	light_purple_blink
lpst	light_purple_strike
c	cyan
cb	cyan_bold
cu	cyan_underline
ci	cyan_italic
cd	cyan_dimmed
cr	cyan_reverse
cbl	cyan_blink
cst	cyan_strike
lc	light_cyan
lcb	light_cyan_bold
lcu	light_cyan_underline
lci	light_cyan_italic
lcd	light_cyan_dimmed
lcr	light_cyan_reverse
lcbl	light_cyan_blink
lcst	light_cyan_strike
w	white
wb	white_bold
wu	white_underline
wi	white_italic
wd	white_dimmed
wr	white_reverse
wbl	white_blink
wst	white_strike
dgr	dark_gray
dgrb	dark_gray_bold
dgru	dark_gray_underline
dgri	dark_gray_italic
dgrd	dark_gray_dimmed
dgrr	dark_gray_reverse
dgrbl	dark_gray_blink
dgrst	dark_gray_strike

"#hex" format

---

The "#hex" format is one way you typically see colors represented. It's simply the # character followed by 6 characters. The first two are for red, the second two are for green, and the third two are for blue. It's important that this string be surrounded in quotes, otherwise Nushell thinks it's a commented out string.

Example: The primary red color is "#ff0000" or "#FF0000". Upper and lower case in letters shouldn't make a difference.

This "#hex" format allows us to specify 24-bit truecolor tones to different parts of Nushell.

full "#hex" format

---

The full "#hex" format is a take on the "#hex" format but allows one to specify the foreground, background, and attributes in one line.

Example: { fg: "#ff0000" bg: "#0000ff" attr: b }

• foreground of red in "#hex" format
• background of blue in "#hex" format
• attribute of bold abbreviated

Primitive values

---

Primitive values are things like int and string. Primitive values and shapes can be set with a variety of color symbologies seen above.

This is the current list of primitives. Not all of these are configurable. The configurable ones are marked with *.

primitive	default color	configurable
any
binary	Color::White.normal()	*
block	Color::White.normal()	*
bool	Color::White.normal()	*
cellpath	Color::White.normal()	*
condition
custom
date	Color::White.normal()	*
duration	Color::White.normal()	*
expression
filesize	Color::White.normal()	*
float	Color::White.normal()	*
glob
import
int	Color::White.normal()	*
list	Color::White.normal()	*
nothing	Color::White.normal()	*
number
operator
path
range	Color::White.normal()	*
record	Color::White.normal()	*
signature
string	Color::White.normal()	*
table
var
vardecl
variable

special "primitives" (not really primitives but they exist solely for coloring)

primitive	default color	configurable
leading_trailing_space_bg	Color::Rgb(128, 128, 128))	*
header	Color::Green.bold()	*
empty	Color::Blue.normal()	*
row_index	Color::Green.bold()	*
hints	Color::DarkGray.normal()	*

Here's a small example of changing some of these values.

> let config = {
    color_config: {
        separator: purple
        leading_trailing_space_bg: "#ffffff"
        header: gb
        date: wd
        filesize: c
        row_index: cb
        bool: red
        int: green
        duration: blue_bold
        range: purple
        float: red
        string: white
        nothing: red
        binary: red
        cellpath: cyan
        hints: dark_gray
    }
}

Here's another small example using multiple color syntaxes with some comments.

> let config = {
    color_config: {
        separator: "#88b719" # this sets only the foreground color like PR #486
        leading_trailing_space_bg: white # this sets only the foreground color in the original style
        header: { # this is like PR #489
            fg: "#B01455", # note, quotes are required on the values with hex colors
            bg: "#ffb900", # note, commas are not required, it could also be all on one line
            attr: bli # note, there are no quotes around this value. it works with or without quotes
        }
        date: "#75507B"
        filesize: "#729fcf"
        row_index: {
            # note, that this is another way to set only the foreground, no need to specify bg and attr
            fg: "#e50914"
        }
    }
}

Shape values

As mentioned above, shape is a term used to indicate the syntax coloring.

Here's the current list of flat shapes.

shape	default style	configurable
shape_block	fg(Color::Blue).bold()	*
shape_bool	fg(Color::LightCyan)	*
shape_custom	bold()	*
shape_external	fg(Color::Cyan)	*
shape_externalarg	fg(Color::Green).bold()	*
shape_filepath	fg(Color::Cyan)	*
shape_flag	fg(Color::Blue).bold()	*
shape_float	fg(Color::Purple).bold()	*
shape_garbage	fg(Color::White).on(Color::Red).bold()	*
shape_globpattern	fg(Color::Cyan).bold()	*
shape_int	fg(Color::Purple).bold()	*
shape_internalcall	fg(Color::Cyan).bold()	*
shape_list	fg(Color::Cyan).bold()	*
shape_literal	fg(Color::Blue)	*
shape_nothing	fg(Color::LightCyan)	*
shape_operator	fg(Color::Yellow)	*
shape_range	fg(Color::Yellow).bold()	*
shape_record	fg(Color::Cyan).bold()	*
shape_signature	fg(Color::Green).bold()	*
shape_string	fg(Color::Green)	*
shape_string_interpolation	fg(Color::Cyan).bold()	*
shape_table	fg(Color::Blue).bold()	*
shape_variable	fg(Color::Purple)	*

Here's a small example of how to apply color to these items. Anything not specified will receive the default color.

> $env.config = {
    color_config: {
        shape_garbage: { fg: "#FFFFFF" bg: "#FF0000" attr: b}
        shape_bool: green
        shape_int: { fg: "#0000ff" attr: b}
    }
}

Prompt configuration and coloring

The Nushell prompt is configurable through these environment variables and config items:

• PROMPT_COMMAND: Code to execute for setting up the prompt (block)
• PROMPT_COMMAND_RIGHT: Code to execute for setting up the RIGHT prompt (block) (see oh-my.nu in nu_scripts)
• PROMPT_INDICATOR = "〉": The indicator printed after the prompt (by default ">"-like Unicode symbol)
• PROMPT_INDICATOR_VI_INSERT = ": "
• PROMPT_INDICATOR_VI_NORMAL = "v "
• PROMPT_MULTILINE_INDICATOR = "::: "
• render_right_prompt_on_last_line: Bool value to enable or disable the right prompt to be rendered on the last line of the prompt

Example: For a simple prompt one could do this. Note that PROMPT_COMMAND requires a block whereas the others require a string.

> $env.PROMPT_COMMAND = { build-string (date now | format date '%m/%d/%Y %I:%M:%S%.3f') ': ' (pwd | path basename) }

If you don't like the default PROMPT_INDICATOR you could change it like this.

> $env.PROMPT_INDICATOR = "> "

If you're using starship, you'll most likely want to show the right prompt on the last line of the prompt, just like zsh or fish. You could modify the config.nu file, just set render_right_prompt_on_last_line to true:

config {
    render_right_prompt_on_last_line = true
    ...
}

Coloring of the prompt is controlled by the block in PROMPT_COMMAND where you can write your own custom prompt. We've written a slightly fancy one that has git statuses located in the nu_scripts repo.

Transient prompt

If you want a different prompt displayed for previously entered commands, you can use Nushell's transient prompt feature. This can be useful if your prompt has lots of information that is unnecessary to show for previous lines (e.g. time and Git status), since you can make it so that previous lines show with a shorter prompt.

Each of the PROMPT_* variables has a corresponding TRANSIENT_PROMPT_* variable to be used for changing that segment when displaying past prompts: TRANSIENT_PROMPT_COMMAND, TRANSIENT_PROMPT_COMMAND_RIGHT, TRANSIENT_PROMPT_INDICATOR, TRANSIENT_PROMPT_INDICATOR_VI_INSERT, TRANSIENT_PROMPT_INDICATOR_VI_NORMAL, TRANSIENT_PROMPT_MULTILINE_INDICATOR. By default, the PROMPT_* variables are used for displaying past prompts.

For example, if you want to make past prompts show up without a left prompt entirely and leave only the indicator, you can use:

> $env.TRANSIENT_PROMPT_COMMAND = ""

If you want to go back to the normal left prompt, you'll have to unset TRANSIENT_PROMPT_COMMAND:

> hide-env TRANSIENT_PROMPT_COMMAND

LS_COLORS colors for the ls command

Nushell will respect and use the LS_COLORS environment variable setting on Mac, Linux, and Windows. This setting allows you to define the color of file types when you do a ls. For instance, you can make directories one color, _.md markdown files another color, _.toml files yet another color, etc. There are a variety of ways to color your file types.

There's an exhaustive list here, which is overkill, but gives you an rudimentary understanding of how to create a ls_colors file that dircolors can turn into a LS_COLORS environment variable.

This is a pretty good introduction to LS_COLORS. I'm sure you can find many more tutorials on the web.

I like the vivid application and currently have it configured in my config.nu like this. You can find vivid here.

$env.LS_COLORS = (vivid generate molokai | str trim)

If LS_COLORS is not set, nushell will default to a built-in LS_COLORS setting, based on 8-bit (extended) ANSI colors.

Theming

Theming combines all the coloring above. Here's a quick example of one we put together quickly to demonstrate the ability to theme. This is a spin on the base16 themes that we see so widespread on the web.

The key to making theming work is to make sure you specify all themes and colors you're going to use in the config.nu file before you declare the let config = line.

# let's define some colors

let base00 = "#181818" # Default Background
let base01 = "#282828" # Lighter Background (Used for status bars, line number and folding marks)
let base02 = "#383838" # Selection Background
let base03 = "#585858" # Comments, Invisibles, Line Highlighting
let base04 = "#b8b8b8" # Dark Foreground (Used for status bars)
let base05 = "#d8d8d8" # Default Foreground, Caret, Delimiters, Operators
let base06 = "#e8e8e8" # Light Foreground (Not often used)
let base07 = "#f8f8f8" # Light Background (Not often used)
let base08 = "#ab4642" # Variables, XML Tags, Markup Link Text, Markup Lists, Diff Deleted
let base09 = "#dc9656" # Integers, Boolean, Constants, XML Attributes, Markup Link Url
let base0a = "#f7ca88" # Classes, Markup Bold, Search Text Background
let base0b = "#a1b56c" # Strings, Inherited Class, Markup Code, Diff Inserted
let base0c = "#86c1b9" # Support, Regular Expressions, Escape Characters, Markup Quotes
let base0d = "#7cafc2" # Functions, Methods, Attribute IDs, Headings
let base0e = "#ba8baf" # Keywords, Storage, Selector, Markup Italic, Diff Changed
let base0f = "#a16946" # Deprecated, Opening/Closing Embedded Language Tags, e.g. <?php ?>

# we're creating a theme here that uses the colors we defined above.

let base16_theme = {
    separator: $base03
    leading_trailing_space_bg: $base04
    header: $base0b
    date: $base0e
    filesize: $base0d
    row_index: $base0c
    bool: $base08
    int: $base0b
    duration: $base08
    range: $base08
    float: $base08
    string: $base04
    nothing: $base08
    binary: $base08
    cellpath: $base08
    hints: dark_gray

    # shape_garbage: { fg: $base07 bg: $base08 attr: b} # base16 white on red
    # but i like the regular white on red for parse errors
    shape_garbage: { fg: "#FFFFFF" bg: "#FF0000" attr: b}
    shape_bool: $base0d
    shape_int: { fg: $base0e attr: b}
    shape_float: { fg: $base0e attr: b}
    shape_range: { fg: $base0a attr: b}
    shape_internalcall: { fg: $base0c attr: b}
    shape_external: $base0c
    shape_externalarg: { fg: $base0b attr: b}
    shape_literal: $base0d
    shape_operator: $base0a
    shape_signature: { fg: $base0b attr: b}
    shape_string: $base0b
    shape_filepath: $base0d
    shape_globpattern: { fg: $base0d attr: b}
    shape_variable: $base0e
    shape_flag: { fg: $base0d attr: b}
    shape_custom: {attr: b}
}

# now let's apply our regular config settings but also apply the "color_config:" theme that we specified above.

let config = {
  filesize_metric: true
  table_mode: rounded # basic, compact, compact_double, light, thin, with_love, rounded, reinforced, heavy, none, other
  use_ls_colors: true
  color_config: $base16_theme # <-- this is the theme
  use_grid_icons: true
  footer_mode: always #always, never, number_of_rows, auto
  animate_prompt: false
  float_precision: 2
  use_ansi_coloring: true
  filesize_format: "b" # b, kb, kib, mb, mib, gb, gib, tb, tib, pb, pib, eb, eib, auto
  edit_mode: emacs # vi
  max_history_size: 10000
  log_level: error
}

if you want to go full-tilt on theming, you'll want to theme all the items I mentioned at the very beginning, including LS_COLORS, and the prompt. Good luck!

Working on light background terminal

Nushell's default config file contains a light theme definition, if you are working on a light background terminal, you can apply the light theme easily.

# in $nu.config-path
$env.config = {
  ...
  color_config: $dark_theme   # if you want a light theme, replace `$dark_theme` to `$light_theme`
  ...
}

You can just change it to light theme by replacing $dark_theme to $light_theme

# in $nu.config-path
$env.config = {
  ...
  color_config: $light_theme   # if you want a light theme, replace `$dark_theme` to `$light_theme`
  ...
}

Accessibility

It's often desired to have the minimum amount of decorations when using a screen reader. In those cases, it's possible to disable borders and other decorations for both table and errors with the following options:

# in $nu.config-path
$env.config = {
  ...
  table: {
   ...
    mode: "none"
   ...
  }
  error_style: "plain"
  ...
}

Line editor menus (completion, history, help…)

Reedline (Nu’s line editor) style is not using the color_config key. Instead, each menu has its own style to be configured separately. See the section dedicated to Reedline’s menus configuration to learn more on this.