seafly is a clean and fast command prompt for the Bash shell heavily inspired by the Pure ZSH prompt.

🚀 For maximum repository performance, seafly will use, if available, either the git-status-fly or git-status-snap utilities. Note, it is strongly recommened to use either of these utilities to accelerate prompt performance.

Screenshot

The font in use is Iosevka.

Layout

seafly is a prompt that displays the following segments when using the default layout:

<Optional Prefix> <Optional User/Host> <Current Path> <Git Branch> <Git Indicators> <Prompt Symbol>

Note, when SEAFLY_LAYOUT=2 is set the prompt will instead display as:

<Optional Prefix> <Optional User/Host> <Git Branch> <Git Indicators> <Current Path> <Prompt Symbol>

seafly can also display as a multiline prompt when SEAFLY_MULTILINE=1 is set. The layout will be the same as listed above but with additional newlines prior to the prefix and prompt symbol.

Please refer to the configuration section below for more details.

Behaviour

• When in a Git repository the checked out Git branch will be displayed.

• When in a Git repository, dirty state, upstream and stash indicators will be displayed. Note, these can individually be disabled if desired.

• The prompt symbol will change to an alert color, by default red, if the last command did not execute successfully.

Visuals

seafly by default will use Unicode characters for the prompt symbol and certain Git indicators. These symbols will display correctly when using a modern font such as Iosevka.

Also, seafly by default will use colors that favour a dark background.

Both the symbols and colors used by seafly can be overridden, please refer to the configuration section below. As an example, the following configuration will:

• only use ASCII characters
• use colors appropriate for a light terminal theme
• style the Git section to mimic $(__git_ps1) provided by the git-prompt.sh script that ships with Git

SEAFLY_PROMPT_SYMBOL=">"
SEAFLY_PS2_PROMPT_SYMBOL=">"
SEAFLY_GIT_PREFIX="("
SEAFLY_GIT_SUFFIX=")"
SEAFLY_GIT_DIRTY="*"
SEAFLY_GIT_STASH="$"
SEAFLY_GIT_AHEAD=">"
SEAFLY_GIT_BEHIND="<"
SEAFLY_GIT_DIVERGED="<>"
SEAFLY_SUCCESS_COLOR="$(tput setaf 63)"
SEAFLY_ALERT_COLOR="$(tput setaf 202)"
SEAFLY_HOST_COLOR="$(tput setaf 242)"
SEAFLY_GIT_COLOR="$(tput setaf 99)"
SEAFLY_PATH_COLOR="$(tput setaf 70)"
. ~/.bash-seafly-prompt/command_prompt.bash

Requirements

A modern 256 or true color terminal is required.

Please also make sure the TERM environment variable is set to xterm-256color, screen-256color or equivalent terminal setting.

For example setting TERM to xterm-256color is usually done at the terminal level either in a preferences dialog or a related configuration file, if required at all. Note, some modern terminals will automatically set 256 colors by default, for example, modern versions of Gnome Terminal.

Setting TERM to screen-256color should only be done for tmux sessions. If you are a tmux user then please add the following to your ~/.tmux.conf file:

set -g default-terminal "screen-256color"
set -ga terminal-overrides ',xterm-256color:Tc'

Note, modern terminals such as Alacritty and kitty provide their own terminfo definitions which are also supported by seafly prompt.

Installation

Install the seafly prompt script:

git clone --depth 1 https://github.com/bluz71/bash-seafly-prompt ~/.bash-seafly-prompt

Source the seafly prompt script in your ~/.bashrc file:

. ~/.bash-seafly-prompt/command_prompt.bash

Note, to update to the latest version of seafly:

cd ~/.bash-seafly-prompt
git pull

git-status-fly

The git-status-fly utility is a simple Rust implemented git status parser. Processing the output of git status using shell commands, such as grep and awk, is much slower than using an optimized binary such as git-status-fly.

Install the git-status-fly somewhere in the current $PATH.

git-status-snap

The git-status-snap utility is an alternative Crystal implemented git status parser. Implementation and behaviour is the same as git-status-fly.

Install the git-status-snap somewhere in the current $PATH.

Git Performance

seafly provides two ways to gather Git status, the previously mentioned git-status-fly or git-status-snap utilities, or a fallback method which collates details using just the git command.

Which to use? See the following performance results and decide.

Performance metrics are listed for the following four repositories:

• dotfiles, small repository with 189 managed files
• rails, medium repository with 4,574 managed files
• linux, large repository with 79,878 managed files
• chromium, extra large repository with 413,542 managed files

Listed is the average time to compute the prompt function.

Linux desktop with NVMe storage:

Repository	git-status-fly	git-status-snap	git fallback
dotfiles	5ms	6ms	11ms
rails	7ms	7ms	14ms
linux(*)	26ms	26ms	38ms
chromium (*)	122ms	123ms	154ms

M1 Macbook Air:

Repository	git-status-fly	git-status-snap	git fallback
dotfiles	33ms	39ms	61ms
rails	39ms	43ms	73ms
linux (!)	60ms	64ms	105ms
chromium (!)	103ms	108ms	155ms

• (*), the git config feature.manyFiles true option was enabled as documented here

• (!), in addition to enabling manyFiles, the git config core.fsmonitor true file system monitor was also enabled as documented here

Note, as of May 2023 fsmonitor is implemented only for Windows and macOS, it is not available for Linux.

In practise, a prompt startup time under 40ms feels instant.

Configuration

Certain behaviours and visuals of the seafly prompt can be controlled through environment variables.

Note, a dash character denotes an unset default value.

Environment Variables

Option	Description	Default Value
SEAFLY_LAYOUT	Specify the preferred layout. Layout 1 will display path followed Git details. Layout 2 will flip the path and Git details.	1
SEAFLY_MULTILINE	Specify multiline layout. SEAFLY_MULTILINE=1 will display the prompt over multiple lines.	0
SEAFLY_SHOW_USER	Display the current user in the user/host segment. Set to 1 to display the user. Refer to SEAFLY_SHOW_USERHOST_CONNECTED.	0
SEAFLY_SHOW_HOST	Display the current hostname in the user/host segment. Set to 0 to not display the host. Ref to SEAFLY_SHOW_USERHOST_CONNECTED.	1
SEAFLY_SHOW_USERHOST_CONNECTED	Display the user/host segment only when connected to external hosts. Set to 0 to always the user/host segment.	1
PROMPT_DIRTRIM	Shorten the current directory path to a set maximum number of components. Set to 0 to not shorten the current path.	4
GIT_PS1_SHOWDIRTYSTATE	Indicate the presence of Git modifications. Set to 0 to skip.	1
GIT_PS1_SHOWSTASHSTATE	Indicate the presence of Git stashes. Set to 0 to skip.	1
GIT_PS1_SHOWUPSTREAM	Indicate differences exist between HEAD and upstream in a Git remote-tracking branch. Set to 0 to skip.	1

Hooks

Hook	Description	Default Value
seafly_pre_command_hook	A function hook to run each time the prompt is displayed. Please make sure the hook is fast.	-
seafly_prompt_prefix_hook	A function hook to populate the optional prefix segment. Please make sure the hook is simple and fast.	-

• A pre_command_hook example that appends and updates history each time the prompt is executed:

  seafly_pre_command_hook="seafly_pre_command"
  
  seafly_pre_command() {
      history -a && history -n
  }

• A prompt_prefix_hook example that displays the current Node version if package.json file is present or displays the name of the current Python virtual environment if one is active in the optional prefix segment:

  seafly_prompt_prefix_hook="seafly_prompt_prefix"
  
  seafly_prompt_prefix() {
      if [[ -f package.json ]]; then
          echo "($(nvm current))"
      elif [[ -n $VIRTUAL_ENV ]]; then
          echo "($(basename $VIRTUAL_ENV))"
      fi
  }

Symbols

Option	Description	Default Value
SEAFLY_PROMPT_SYMBOL	The prompt symbol	❯
SEAFLY_PS2_PROMPT_SYMBOL	The PS2 secondary prompt symbol	❯
SEAFLY_GIT_PREFIX	Symbol to the left of the Git branch	
SEAFLY_GIT_SUFFIX	Symbol to the right of the Git indicators	-
SEAFLY_GIT_DIRTY	Symbol indicating that a Git repository contains modifications	✗
SEAFLY_GIT_STAGED	Symbol indicating that a Git repository contains staged changes	✓
SEAFLY_GIT_STASH	Symbol indicating that a Git repository contains one or more stashes	⚑
SEAFLY_GIT_AHEAD	Symbol indicating that a Git remote-tracking branch is ahead of upstream	↑
SEAFLY_GIT_BEHIND	Symbol indicating that a Git remote-tracking branch is behind upstream	↓
SEAFLY_GIT_DIVERGED	Symbol indicating that a Git remote-tracking branch is both ahead and behind upstream	↕

Colors

The default color values listed below, such as 111 and 203, derive from xterm 256 color values. Please refer to this chart when customizing seafly colors.

Option	Description	Default Value	Color
SEAFLY_PREFIX_COLOR	Optional prefix segment	217
SEAFLY_SUCCESS_COLOR	Standard prompt and certain Git indicators	111
SEAFLY_ALERT_COLOR	Alert prompt and Git dirty indicator	203
SEAFLY_HOST_COLOR	Host segment	255
SEAFLY_GIT_COLOR	Git branch, stash and optional prefix/suffix	147
SEAFLY_PATH_COLOR	Current directory path	114

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