shell whisperer

This is a very small library to provide a wrapper around Ruby's backtick thing, where you can run shell commands.

Installation

Add this line to your application's Gemfile:

gem 'shell_whisperer'

And then execute:

$ bundle

Or install it yourself as:

$ gem install shell_whisperer

Usage

Happy path (the command succeeds and outputs something):

ShellWhisperer.run "ls" #=> "README.md\n"
ShellWhisperer.run "cat README.md" #=> "Content of README.md\n"

Sad path (the command fails and prints an error):

begin
  ShellWhisperer.run "cat README.dm"
rescue ShellWhisperer::CommandFailed => e
  e #=> #<ShellWhisperer::CommandFailed: Attempted to run "cat README.dm" but the shell reported error: "cat: README.dm: No such file or directory" and exited with exit code 1.>
  e.original_command #=> "cat README.dm"
  e.original_message #=> "cat README.dm: No such file or directory \n"
  e.exit_code #=> 1
end

The goal is that you have a nice way of capturing output of a command while also having a nice way of knowing why something failed, if it failed.

Here's a caveat:

ShellWhisperer.run("cat README.md | wc -l").to_i #=> 69
ShellWhisperer.run("cat README.dm | wc -l").to_i #=> 0

What!? Shouldn't the second one have failed, because the README.dm file does not exist? Well, maybe, but it pipes its output to wc, and wc succeeds, so ShellWhisperer thinks the whole thing succeeded. For this reason, it might make more sense to write this example like:

ShellWhisperer.run("cat README.dm").each_line.count

Which will fail in the desired way.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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 rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/maxjacobson/shell_whisperer. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.