qb-prompt is an easily-customizable bash prompt, which tries to combine good look and powerfull features with the best possible performance.
It is visually inspired by Powerline, which implements beautiful status lines and prompts for vim, tmux, bash, zsh and some other apps. qb-prompt aims to provide similar look and feel, but focuses on bash prompt only, which gives a freedom for the more efficient approach (more details below).
qb-prompt supports several "widgets" (as I call parts of the prompt here), which can be toggled, reordered and variously configured by input configuration file:
- User marker - indicates if the current user is root or not with markers (
$and#) and colors - User name - current user's name with different colors for root and non-roots
- Current directory - prettified current directory path, shortened in the middle if too long
- Error code - indicates last return code, if non-zero
- Background jobs - prints the number of background processes, if any
- SSH marker - indicator of SSH connection
- SSH address - indicator of SSH connection with the server address
- Git marker - indicator of git repository
- Git branch - indicator of git repository with current branch
- Custom - any text or bash prompt special character decorated by qb-prompt. In fact, simplified alternatives for the majority of above widgets can be implemented using it
If you come up with a useful widget idea that can't be implemented by 'Custom' widget - feel free to suggest here
Video overview (youtube) (a little outdated)
- User configures prompts (enabled widgets, their alignment side, position, colors, decorations, etc) in simple JSON-formatted file
- Then the python script
generate.pyuses it to generate not very human-readable but highly efficient shell scriptqb-prompt.sh. It is called only once when configuration is changed, there is no python code in runtime! qb-prompt.shprovides ready to use prompts (environment variablesPS1,PS2,PS3,PS4andPROMPT_COMMANDdepending on configuration) for bash interpreter and should be simply sourced frombashrcfile.
Generation stage tries to statically resolve needed values and hardcode them into the final script to minimize the runtime of the final script. However it is not always possible: some values must be evaluated every time you log in to shell (like ssh address, user highlighting color), and some values must be evaluated every time the prompt is printed (like background jobs number, error code, git branch, etc). It might have noticable effect on the performance, so choose widgets thoughtfully when configuring (although I haven't noticed any lag even with full feature set enabled). You can try different configs and compare the complexity of the resulting qb-prompt.sh.
This approach allows having both: convenient configuration and the best performance.
1. Install dependencies
qb-prompt uses Powerline fonts. Check out this link for installation instructions. Some Linux distros have a package for it in their repos. For example, powerline-fonts in ArchLinux, fonts-powerline in Ubuntu.
Strictly saying, Powerline fonts is a (very) recommended dependency, but not required. The default config uses it for widget transitions, directory separators, etc, but you can change them to any characters you like. Although if you want these beatiful arrowed backgrounds - you need Powerline fonts.
2. Get qb-prompt.sh
Simple way: download qb-prompt.sh generated with default configuration from repository
wget https://raw.githubusercontent.com/azymohliad/qb-prompt/master/qb-prompt.sh
Note that default config doesn't include git branch and ssh address widgets.
Customizable way: generate it from your own configuration
- Download or clone the repostory files
git clone https://github.com/azymohliad/qb-prompt.git && cd qb-prompt
- Define your configuration in a config file (e.g.
config.json). You can check sample_configs as a starting point and customize them for your needs and taste. Check out CONFIGURATION.md for more details - Generate
qb-prompt.sh:
./generate.py [your/input/config.json] [your/output/qb-prompt.sh]
3. Source it from your bashrc file.
Add these lines to the end of your ~/.bashrc (for the current user) or /etc/bash.bashrc (for all users):
# qb-prompt
. /path/to/qb-prompt.sh
4. Relogin to your bash and have fun
To profile the primary prompt rendering time I calculate the difference between timestamps at the end of PS1 and at the beginning of PROMPT_COMMAND. Timestamps are taken with date +%s%N bash command.
To profile the script initial loading time I took the difference between timestamps at the end and at the beginning of the script.
Here are the benchmarking results of primary prompt rendering time on my machine for sample configurations while navigating the terminal for few minutes:
| Configuration | Min | Avg | Max |
|---|---|---|---|
| default | 6.86 ms | 11.27 ms | 17.32 ms |
| default_simplified_dir | 3.38 ms | 6.45 ms | 9.52 ms |
| feature_rich | 8.77 ms | 15.82 ms | 25.47 ms |
| minimal | 2.10 ms | 3.79 ms | 5.64 ms |
| user_dir_dynamic | 5.45 ms | 9.57 ms | 16.11 ms |
| user_dir_simple | 1.76 ms | 3.95 ms | 6.93 ms |
Script loading time was always under 10 ms.
My software and hardware:
Software: Tilix, ArchLinux, Gnome 3.28, Xorg
Hardware: Intel Core i5-4310M CPU @ 2.70GHz, 8GB DDR3 RAM, integrated Intel graphics, 5400rpm HDD
There is not much to do here. Feel free to report issues or suggest small improvements (including features, performance optimizations, coding style etc). But one of my priorities is to keep it lightweight and fast, so I might be sceptic about new features.
Licensed under the MIT license.