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A Unix shell for Ruby programmers.
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Latest commit 8a54c1e Jun 29, 2015 @Spakman Fix race when opening first 2 Urchin instances
Fixes #23.

Tested-by: Mark Somerville <> [Arch, MRI 2.2.2]
Signed-off-by: Mark Somerville <>
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bin Aliases are now stored per Shell instance Jun 24, 2015
completion Add _ builtin to manipulate running Urchin instance Aug 16, 2013
lib Use Kernel#abort instead of Kernel#exit for errors Jun 24, 2015
Rakefile Add a .gemspec file Jul 14, 2011
boot.rb Follow the XDG Base Directory Specification[1] Jun 29, 2015
environment.rb Fix race when opening first 2 Urchin instances Jun 29, 2015
urchin.gemspec Update startup for rb-readline 0.5.1 Jan 21, 2014



A Unix shell for Ruby programmers.

If you have any ideas for what you think this should mean, please submit a

Urchin does not aim to be POSIX compliant, but is heavily influenced by Bash
and Zsh. Urchin aims to make Ruby a first class citizen in the shell and be a
good place for experimenting with new shell ideas.


Mark Somerville <>
Spakman on Freenode

Current status

Preparing to release version 0.2.0. On Linux this will be beta quality. It is
considerably less tested on other platforms. I have been using it as my login
shell since version 0.1.0 and it has been pretty stable.

Quite a lot of common Unix shell stuff is implemented: job control,
redirections, tilde expansion, aliasing, globbing and environment variables.
Functions are the most obvious thing missing from that list. These will most
likely appear in 0.3.0.

Straightforward inline Ruby is available! This was the original inspiration for
the project (although the vision has grown somewhat now). This allows writing
Ruby processes directly on the command line, without the need to escape special
characters. This will likely be expanded and improved upon in later releases.

I will create a gem for version 0.2.0.

Current problems

GitHub is used for ticket tracking:


Tested with MRI 1.8.7, 1.9.2 and 1.9.3-dev on Linux.

If running using 1.9.2 on a laptop, be aware of bug #3436
( This should be fixed when
1.9.3 is released.

Since version 0.2.0, Urchin relies on rb-readline. Use the latest version or
check it out from GitHub[1]. I'm one of the maintainers for rb-readline and
always check that Urchin works with the latest version.

1 -

Tested with version 0.9.6.

Some examples that work


	ls -la | head -n2

Calling a new Ruby process (~@ is the default delimiter):

	ls --no-color |~@ puts ~@ | sort
	ls --no-color |~@ o s.reverse ~@ | sort


	uptime > output
	uptime >> output
	ruby -e 'puts; STDERR.puts 33' < input > out_and_err 2>&1

Backgrounding jobs:

	sleep 60 &

Multiple jobs:

	sleep 60 & man sleep

	sleep 60; echo "it's over"

Quoted and unquoted parameters:

	grep -r '"hello"' .
	grep -r "\"hello\"" .
	ls my\ annoyingly\ named\ dir
	find . -name 'hello' -exec chmod 660 {} \;


	ls **/*.rb
	mv image?.{png,gif} images

Tilde expansion:

	ls ~/src/
	ls ~mark

Reading and setting environment variables:

	echo $PATH
	echo abx${HOME}xyz
	export HELLO="Yo man!"

Simple arithmetic (lines starting with a digit are eval-ed as Ruby):

	17 * 123

Command expansion:

	ps `pgrep urchin`

Job control (uses fg, bg and jobs builtins).
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