Making a custom zsh theme: for fun and aesthetic.

TLDR:

This article gives an introduction on how to modify the existing zsh theme to one's own liking.

Source Code: github

Back story:

As being a React Native Developer I’ve to spend a lot of time looking at my iterm2 terminal emulator. So I decided to make that emulator look prettier.

I am using zsh with my iterm2. So, like any other beginner, I have installed oh-my-zsh. oh-my-zsh got many themes. I am particularly interested in the minimalistic theme robbyrussell.zsh-theme.

I liked the look and feel, it doesn’t bombard me with a bunch of information that according to my preferences I don’t need. Like the full path of my current directory. Don’t get me wrong, many of you may need that information for your workflow but in my case, I don’t need that.

Although I like the simple approach I want something that I can tell that "this is mine". So I have tried modifying it to my likings. This article describes my journey.

Prerequisite:

This article is for those who knows/have

1. zsh installed
2. oh-my-zsh installed
3. iterm2 (or any other terminal emulator that supports 24 bit color or true color) installed

?Set up:

After doing the all the things in previous prerequisite section go to the following directory

cd .oh-my-zsh/custom/themes/

Now create a file with the extension .zsh-theme (in my case I named the file as mrp.zsh-theme) and copy-paste the content of robbyrussell.zsh-theme to our customer .zsh-theme file.

Now open ~.zshrc file and put the following line

ZSH_THEME="mrp"

PROMPT:

Now let's look at the first line of our robbyrussell.zsh-theme

Here the prompt follow the following pattern

%(?:true-text:false-text)

It specifies a ternary expression. Meaning it checks for condition, if the condition returns true then it will show ‘true-text’ in the prompt, otherwise it will show ‘false-text’. Here the condition is specified by the "?” mark, which indicates whether or not the last command was executed successfully. If the last command executes successfully then the true-text will show on prompt, otherwise, the false-text will show.

Now let’s look at our formatting of true-text. Our true-text is divided into two parts. One defines the formatting and color and the other defines actual things to show.

1st part

%{$fg_bold[green]%}

It follows the following pattern

%{...%}

We define our colors and the formatting between them. Here, it uses the pattern of ‘colors’ function that ships with zsh by default.

We can define colors in three ways:

1. we can use named color (used in robbyrussell.zsh-theme) instead of ‘green’ and in place of fg_bold the following settings can be used:

1. for foreground: fg, fg_bold, and fg_no_bold

2. for background bg, bg_bold, and bg_no_bold

2. Another way of setting colors is using the following pattern

$FG[202]

so our code of true-text will be

$FG[255]?

oh-my-zsh uses Spectrum under the hood to define the color code 0-255. You can visualize the whole set of color by running the following command

spectrum_ls # without background

spectrum_bls # with background

3. However we are using the third way using the following pattern

%F{HEX_CODE}

iterm2 supports true color . So we can use any hex color code. let give the hex color for both true-text and false-text. After that our code for prompt should look like the following

our terminal now looks like the following:

Now let's change the arrow sign to the apple logo.

After searching for a long time I’ve finally found the icon. Here is that apple logo

Now you may not see it here, but just copy-paste that on the prompt code then you’ll the logo on the prompt. After adding the logo our Prompt code should look like the following:

Now our prompt should look like this.

PROMPT+:

Now let’s take a look at the 2nd line of our theme.

There is nothing much to change. we will change some color. First, let’s understand what does it mean:

1. 1st part: which space indicate the spacing from our apple icon to our current directory name
2. 2nd part: “%{$fg[cyan]%}” indicates the color of our current directory. let change it to %{%F{#46b5d1}
3. 3rd part: %c indicates that the prompt will only show the last component of the current directory path.
4. 4th part: in short the string “%{$reset_color” indicates that the input text will be different than the rest of the prompt like the following:

if you delete “%{$reset_color” then the input text will be just like the rest of the prompt like the following:

5. 5th part: “$(git_prompt_info)” indicates that the basic info of git SCM of the current directory will show just after a white space from the current directory like the following:

However, the way that git_prompt_info will show us the information is defined by the following code snippet

ZSH_THEME_GIT_PROMPT_PREFIX="%{$fg_bold[blue]%}git:(%{$fg[red]%}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%} "
ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[blue]%}) %{$fg[yellow]%}?"

ZSH_THEME_GIT_PROMPT_CLEAN="%{$fg[blue]%})"

ZSH_THEME_GIT_PROMPT_PREFIX variable the UI configuration on how the text “git:(” will show. there are 3 parts that this variable contains:

1. “%{$fg_bold[blue]%}” defines the color of the 2nd part (what will actually be showing)

2. “git:(“ , this string will actually be showing.

3. “%{$fg[red]%}” defines the color of the branch name. in our case that is the master branch

ZSH_THEME_GIT_PROMPT_SUFFIX variable ensures the input text color is different from the rest of the prompt.

ZSH_THEME_GIT_PROMPT_DIRTY variable will take effect if the branch is dirty. it contains 4 part

1. “%{$fg[blue]%}” defines the color of 2nd part of 1st bracket
2. “)” 2nd part of that 1st bracket
3. “%{$fg[yellow]%}” define the color the next mark
4. “?” actual mark that will show when the branch is dirty.

 ZSH_THEME_GIT_PROMPT_CLEAN variable defines the rest of the prompt when the branch is clean. it has 2 part

1. “%{$fg[blue]%}” defines the color of the next element
2. “)” actual element to show.

Now let’s make changes in the following places

1. replace all “%{$fg_bold[blue]%}” and “%{$fg[blue]%}” and “%{$fg[red]%}” to this %F{#89C9D9}
2. replace “git:” to “\ue727 -> “ in ZSH_THEME_GIT_PROMPT_PREFIX

After doing all the above your 4 variable related to the git prompt should look like the following 

ZSH_THEME_GIT_PROMPT_PREFIX="%F{#89C9D9}\ue727 -> (%F{#89C9D9}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%} "
ZSH_THEME_GIT_PROMPT_DIRTY="%F{#89C9D9}) %{$fg[yellow]%}?"

ZSH_THEME_GIT_PROMPT_CLEAN="%F{#89C9D9})"

Now your prompt with git info should look like the following.

Now the whole code for our custom prompt should look like the following:

PROMPT="%(?:%F{#46b5d1} :%F{#d16246} )"
PROMPT+=' %{$fg[cyan]%}%c%{$reset_color%} $(git_prompt_info)'


ZSH_THEME_GIT_PROMPT_PREFIX="%F{#89C9D9}\ue727 -> (%F{#89C9D9}"

ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%} "

ZSH_THEME_GIT_PROMPT_DIRTY="%F{#89C9D9}) %{$fg[yellow]%}?"

ZSH_THEME_GIT_PROMPT_CLEAN="%F{#89C9D9})"

That's it for today. If you have any questions feel free to ask.