Shell implements an idiomatic Ruby interface for common UNIX shell commands.

It provides users the ability to execute commands with filters and pipes, like +sh+/+csh+ by using native facilities of Ruby.


Add this line to your application's Gemfile:

gem 'shell'

And then execute:

$ bundle

Or install it yourself as:

$ gem install shell


Temp file creation

In this example we will create three +tmpFile+'s in three different folders under the +/tmp+ directory.

  sh ="/tmp") # Change to the /tmp directory
  sh.mkdir "shell-test-1" unless sh.exists?("shell-test-1")
  # make the 'shell-test-1' directory if it doesn't already exist"shell-test-1") # Change to the /tmp/shell-test-1 directory
  for dir in ["dir1", "dir3", "dir5"]
    if !sh.exists?(dir)
      sh.mkdir dir # make dir if it doesn't already exist do
        # change to the `dir` directory
      f ="tmpFile", "w") # open a new file in write mode
      f.print "TEST\n"            # write to the file
      f.close                     # close the file handler
      print sh.pwd                  # output the process working directory

Temp file creation with self

This example is identical to the first, except we're using CommandProcessor#transact.

CommandProcessor#transact executes the given block against self, in this case +sh+; our Shell object. Within the block we can substitute to +cd+, because the scope within the block uses +sh+ already.

  sh ="/tmp")
  sh.transact do
    mkdir "shell-test-1" unless exists?("shell-test-1")
    for dir in ["dir1", "dir3", "dir5"]
      if !exists?(dir)
      mkdir dir
      cd(dir) do
        f = open("tmpFile", "w")
        f.print "TEST\n"
      print pwd

Pipe /etc/printcap into a file

In this example we will read the operating system file +/etc/printcap+, generated by +cupsd+, and then output it to a new file relative to the +pwd+ of +sh+.

  sh ="/etc/printcap") | sh.tee("tee1") > "tee2"
  ( < "/etc/printcap") | sh.tee("tee11") > "tee12""/etc/printcap") | sh.tee("tee1") >> "tee2"
  ( < "/etc/printcap") | sh.tee("tee11") >> "tee12"


After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at


The gem is available as open source under the terms of the 2-Clause BSD License.