Programming language: Crystal
License: GNU General Public License v3.0 or later
Tags: Shell Plugins    
Latest version: v1.0.2

crun alternatives and similar shards

Based on the "Shell plugins" category.
Alternatively, view crun alternatives based on common mentions on social networks and blogs.

Do you think we are missing an alternative of crun or a related project?

Add another 'Shell plugins' Shard


Travis-CI Build Status CircleCI Build Status Release


Crystal Run : shebang wrapper for Crystal

crun is a tool enabling one to put a "bang line" in the source code of a Crystal program to run it, or to run such a source code file explicitly. It was inspired by gorun and created in an attempt to make experimenting with Crystal more appealing to people used to Ruby and similar languages which operate most visibly with source code.


As an example, copy the following content to a file named "hello.cr" (or "hello", if you prefer):

#!/usr/bin/env crun

puts "Hello world"

Then, simply run it:

$ chmod +x hello.cr
$ ./hello.cr
Hello world!


crun will:

  • write files under a safe directory in $CRUN_CACHE_PATH, $XDG_CACHE_HOME/crun, ~/.cache/crun, ~/.cache/.crun or .crun in this order, so that the actual script location isn't touched (may be read-only)
  • avoid races between parallel compilation of the same file
  • automatically clean up old compiled files that remain unused for some time, by default each 7 days but can be overriden by setting CLEAN_CACHE_DAYS
  • replace the process rather than using a child
  • pass arguments to the compiled application properly
  • handle well shards with comment containing dependencies of a classical shards.yml file. Anchors used can be changed by settings CRUN_SHARDS_START_ANCHOR (default: ---) and CRUN_SHARD_END_ANCHOR (default: ...).

Shards support example

#!/usr/bin/env crun
# ---
# minitest:
#   github: ysbaddaden/minitest.cr
# ...

class Foo
  def bar

require "minitest/autorun"

class FooTest < Minitest::Test
  def foo
    @foo ||= Foo.new

  def test_that_foo_bar_baz
    assert_equal "baz", foo.bar

describe Foo do
  let(:foo) { Foo.new }

  describe "when asked about bar" do
    it "must respond baz" do

Where are the compiled files kept?

They are kept under $CRUN_CACHE_PATH, $XDG_CACHE_HOME/crun, ~/.cache/crun, ~/.cache/.crun or .crun in this order, in a directory named after the hostname and the slug of the source file name.

You can remove these files, but there's no reason to do this. These compiled files will be garbage collected by crun itself after a while once they stop being used. This is done in a fast and safe way so that concurrently executing scripts will not fail to execute.

How to build and install crun from source

make release
make install

You can change PREFIX or BINDIR environment variable, see Makefile


usage: crun <source file> [...]

Add Linux binfmt support

echo ':crystal:E::cr::/usr/local/bin/crun:OC' \
  | sudo tee /proc/sys/fs/binfmt_misc/register


make binfmt


Install Git pre-commit hook

make githook

Makefile help

> make
  auto            Run tests suite continuously on writes
  binfmt          Add Linux binfmt support
  check           Run Ameba static code check
  clean           Remove crun builded binary
  clobber         Clean and remove editor backup files (*~)
  crun            Build crun binary
  format          Run Crystal format tool
  githook         Install Git pre-commit hook
  help            Show this help
  install         Install crun binary
  release         Build crun binary
  spec            Run crun specs
  tests           Run tests suite
  todo            Show fixme and todo comments
  uninstall       Uninstall crun binary

OsX (for fancy autotests / continuous testing)

brew tap veelenga/tap
brew install ameba crystal fswatch imagemagick terminal-notifier


make osx

Debian/Ubuntu (for fancy autotests / continuous testing)

apt install -y -q inotify-tools libnotify-bin


  1. Fork it (https://github.com/Val/crun/fork)
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request


  • Val Laurent Vallar - creator, maintainer
  • bew Benoit de Chezelles