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𓆚 Hydra

a C implementation of Emacs Hydra package to be used in terminal.

asciicast

What is 𓆚 Hydra?

  • An implementation of Emacs 𓆚 Hydra functionality to be used in the terminal
  • a terminal program that groups your commands and bind them to common key on your keyboard.
  • Commands can also be grouped in a tree like structure each node in the tree has a name and key bound to it.
  • It reads CSV files of key,name,command lines then shows Terminal UI similar to Emacs 𓆚 Hydra and prints the command to stdout.

Spacemacs for example is an emacs configuration centered around 𓆚 Hydra commands, with all user commands grouped as trees bound in a mnemonic way. for example:

  • opening a file is bound to space f f
  • deleting current file is bound to space f D
  • Git status space g s

Binding 𓆚 Hydra to space key in your terminal means pressing space will make your terminal behave similar to spacemacs if you executed the output with eval. this repo has a bash script hydra-completion.bash which achieve this binding.

Other usages

  • hydra doesn't execute the command by default.
  • The program prints the choosen command to standard output.
  • What to do with this output is up to you. you can for example append it to a file. or open the browser with the output or whatever. just like fzf and dmenu.
  • Which means you can use 𓆚 Hydra as part of your scripts to allow the user to navigate a tree of choices and get the final choice piped to another program, GNU coreutils style.

Install

  • Clone it from github to your machine
git clone git@github.com:emad-elsaid/hydra.git
cd hydra
  • Build
make
  • Install
sudo make install
  • Export HYDRA variable to your .bashrc. it should have a list of hydras files. 𓆚 Hydra example files are installed under /usr/share/hydra/hydras.
  • Loading /usr/share/hydra-completion.bash will bind hydra to Space key in your keyboard and will invoke hydra when the line is empty.
  • For example to use the git 𓆚 Hydra:
export HYDRA="/usr/share/hydra/hydras/git"
source /usr/share/hydra/hydra-completion.bash

𓆚 Hydra file

  • 𓆚 Hydra files are simple CSV files that define the commands 𓆚 hydra can load.
  • The file has 3 columns without header. an example is under hydras directory in this repo.

a simple example can be as follow

g,Git,
gs,Status,git status
  • It defines Git command that doesn't execute a command under the key g
  • and defines a command named Status under key s inside g that will execute the command git status

Running

  • You can run hydra binary with a list of 𓆚 hydra files
  • 𓆚 Hydra will load the files in the order passed.
  • it will display the list of top level commands
  • When the program reaches a choosen command that doesn't have children it will print the command to standard output
hydra hydras/git hydras/systemd hydras/github

Tests

To run tests execute

make run-test