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Dynamic Prompt

Easily configure and use a responsive prompt that will dynamically show information about your current environment.

IMPORTANT !
Main repo is on Framagit - My Programs / Dynamic Prompt.
On other online git platforms, they are just mirrors of the main repo.
Any issues, pull/merge requests, etc., might not be considered on those other platforms.

Description

This repo contains scripts allowing you to setup a dynamic and "responsive" prompt. As I live mainly in terminal and I mainly do sysadmin, I need to know quickly on which kind of computer I am, personnal, professional, workstation, server, which OpenStack pool variables are loaded, which Kubernetes configuration is loaded, etc.

Note

Its part of my dotfiles repos which optimize my terminal usage. For now, all my dotfiles are not yet clean neither documented. Once done, a link will be provided if you want to learn more about how my terminal usage.

The aims of this prompt are:

  • Support bash and zsh in a transparent way

    Before using this prompt, I used shell frameworks bash-it and oh-my-zsh. So, when I needed to add something, I needed to work on two prompt configuration. I wanted to centralize this to manage both at once. Moreover, my personnal computer use zsh while most server I work on use bash, so I must support both with only one repo and the less possible files.

  • Being fast

    Prompt with all segments must be shown in less than 250ms in average on my computers. In the CI, the average computation time is set to 500ms (because CI is done within docker container and poor hardware). Unfortunately, I can not ensure you this prompt is able to be shown in this amount of time, because this is depending on your hardware1.

  • Being dynamic

    Show informations of the current folder only if there exists. For instance, show python environment informations or git informations only when there exists, k8s cluster namespace only when set, etc.

  • Being responsive

    When terminal emulator is to short, the prompt must shrink informations until hiding them completely when there is not enough space to show all segments.

  • Being fully customizable

    As I used multiple computers, I need to be able to quickly set a common shared configuration (colors, characters, etc) and some computer specific configuration. This must be done by modifiying the less possible files.

  • Being extensible

    If user need to add a new segment, it should be as easy as possible to do so.

  • Being "discrete"

    The computation of the prompt lines should export as few functions and variables as possible, i.e. functions used in this repo can not be called when you can input your command. This is to avoid adding mess in your global variables environment as well as your global functions.

Why this new prompt while there exists similar project like liquidprompt ? (click to reveal)

When I started this prompt, I did not know liquidprompt. After quickly checking the code, here are some differences I saw:

  • Almost all variables used to show this prompt are not exported and so do not add useless variables in your shell environment.
  • This prompt allow you to easily add your own segment.
  • This repo propose you two versions, one quite "classic" and one more "powerline" lool alike. Choosing which version to use is done simply by changing variable PROMPT_VERSION (see Configure your prompt).
  • This prompt may have few dependencies, like the git or the kubectl. But these dependencies are only requires if you use segments which requires these dependencies. In other terms, dependencies are per segments, the core of the prompt does not have any dependencies.
  • Every modification, like changing colors, changing segments used or their order, adding the code of a new segments, etc., is done dynamically, no need to source your ~/.bashrc or ~/.zshrc on every change. Only changes done to the script prompt.sh requires to reload your ~/.bashrc or your ~/.zshrc

I may be wrong as I quickly check the code of liquidprompt and I'm open to take any remark.

What about other similar project ? (click to reveal)

For the moment, I have forgotten some other projects name, but a common things about these projects I remember is that these projects often required external dependencies like node or go.

One of the main goal of this project is to use as low external dependencies as possible. Indeed some segments required external dependencies, like git and other dependencies are required for developing, like mkdocs. But for now, as user, the only dependencies for this prompt are :

  • bash >= 4.0
  • zsh >= 5.0

Prompt description

Prompt illustration

In the following section, I will present the prompt with default prompt line, i.e. default segments organisation, and with the colors provided by the file host/common.example.sh. You will be able change segments organisation and colors as descibed in Configure your prompt.

First of all, this repo propose two "version" of the prompt:

  • The v1 which is kind of "classic" and is also the fallback version.
  • The v2 which is more "powerline" like.

Note

As there is not differences in behaviour neither in display whether you use bash or zsh, the shell will not be specified in all screenshots of this documentation

Here are some screenshots of both prompt version :

  • The v1 is "classic" as show belown for bash and zsh (click on image to enlarge).

Prompt v1

  • The v2 is more "powerline" look alike as shown below for bash and zsh (click on image to enlarge).

Prompt v2

In both case, (almost) all parts (colors, character, which segment to show, in which order, etc.) are customizable. You can either choose to show only some segments or change their colors depending on what you prefer.

The above show the prompt when no "environment" is loaded, i.e. only segment pwd, hostname and username are actually displayed. The colored horizontal line is here to know quickly on which type of computer I am (for instance, red for professional workstation, magenta for professional servers, green for personnal workstation, yellow for personal servers, etc.). All colors of the prompt (the current directory, the username, etc.) can be easily change for each computer based on its hostname as described in Configure your prompt.

Below is what prompt looks like when almost most supported segments are loaded.

Not all supported segment are displayed, because some segments might have be added after taking these screenshots, see below the up-to-date list of supported segments.

  • The v1, "classic" version (click on image to enlarge)

Prompt v1 Full

  • The v2, "powerline" version (click on image to enlarge)

Prompt v2 Full

Supported segments/environment are :

Name Short Description
return_code Exit code of the previous command
hfill Special segment to fill terminal line
pwd Current path
bgjobs Number of background jobs
hostname Hostname of the computer
keepass Keepass variables loaded
kube Kubernetes context
openstack OpenStack context
tmux Tmux windows and pane
username Current username
vcsh Name of the vcsh repo
vcs Version control informations
virtualenv Virtual environment informations

Important

date segment will never be added to the repo as it is use as support to the tutorial Add your own segment and is quite simple to setup 😉.

For every segments, colors and characters can be configured individually to be shown or not (see Configure your prompt).

Moreover, when logged as root all the prompt shift to bold, thus I know visually that I am root and things I do can be dangerous. See below for a examples.

  • The v1, "classic" version (click on image to enlarge)

Prompt v1 root full

  • The v2, "powerline" version (click on image to enlarge)

Prompt v2 root full

Finally, examples above show prompt filling the terminal line, but you can also configure your prompt to have a more "standard" display as shown below:

  • The v1, "classic" version

With few segments (click on image to enlarge)

Prompt v1 "Standard" display

With more segments (click on image to enlarge)

Prompt v1 "Standard" display full

  • The v2, "powerline" version

With few segments (click on image to enlarge)

Prompt v2 "Standard" display

With more segments (click on image to enlarge)

Prompt v2 "Standard" display full

Important

When in tty or in unsupported terminal emulator, prompt will automatically fall back to prompt v1.

Environment contraction

When there is not enough space to show all segments completely, they will be contracted to show minimal informations, usually only the character of the segment.

The more your terminal will shorten, the less segment informations will be shown. Order on which segments are contracted are always in the same order, defined by user (see Configure your prompt). Finally, if there is really not enough space, some information will be completely hidden.

Exemple of contraction are shown below for both prompt version.

  • Prompt v1 (click on image to enlarge)

Prompt v1 Shrink

  • Prompt v2 (click on image to enlarge)

Prompt v2 Shrink

Warning about the contraction behaviour ! (click to reveal)

GIFs above only show contraction behaviour.

But as variable PS1 for bash and PROMPT for zsh are only computed before printing them, i.e. before printing the prompt, when you resize your terminal emulator, you will need to press Enter once to recompute the size of your prompt and so update the display of the prompt.

When resizing your terminal, before pressing Enter, you prompt might look like shown below.

  • When increasing size of terminal emulator

Prompt v1 (click on image to enlarge)

Prompt v1 Increase terminal size

Prompt v2 (click on image to enlarge)

Prompt v2 Increase terminal size

  • When decreasing size of terminal emulator

Prompt v1 (click on image to enlarge)

Prompt v1 Decrease terminal size

Prompt v2 (click on image to enlarge)

Prompt v2 Decrease terminal size

Default prompt colors

By default, if no user configuration exists, no colors will be set, as shown below for both versions.

  • Prompt v1 (click on image to enlarge)

Prompt v1 No Colors

  • Prompt v2 (click on image to enlarge)

Prompt v2 No Colors

Go further & documentation

If you want to try this prompt, view how to configure it and more:

Futur possible updates

Here is a list of idea I may work on one day, if I have the time and/or the will to do so. But these are not guaranteed. However, if you want some of these features and/or you want to contribute in any way, I will be glad to help you.

  • : Test integration with
  • : Propose an automatic/interactive install script.

  1. As information, my two main computers have following hardware configurations:

    • Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz / 16Go DDR4 RAM 1200Mhz
    • Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz / 16Go DDR3 RAM 1333Mhz
    • But I play with some RPi and Brix Gigabyte like (Intel Celeron) 😉

    ↩

Last update: December 9, 2021
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