Cocaine

A small library for doing (command) lines.

Feedback

Question? Idea? Problem? Bug? Something else? Comment? Concern? Like use question marks?

GitHub Issues For All!

Usage

The basic, normal stuff.

line = Cocaine::CommandLine.new("command", "some 'crazy' options")
line.command      # => "command some 'crazy' options"
output = line.run # => Get you some output!

Allowing arguments to be dynamic:

line = Cocaine::CommandLine.new("convert", ":in -scale :resolution :out",
                                :in => "omg.jpg",
                                :resolution => "32x32",
                                :out => "omg_thumb.jpg")
line.command # => "convert 'omg.jpg' -scale '32x32' 'omg_thumb.jpg'"

It prevents attempts at being bad:

line = Cocaine::CommandLine.new("cat", ":file", :file => "haha`rm -rf /`.txt")
line.command # => "cat 'haha`rm -rf /`.txt'"

line = Cocaine::CommandLine.new("cat", ":file", :file => "ohyeah?'`rm -rf /`.ha!")
line.command # => "cat 'ohyeah?'\\''`rm -rf /`.ha!'"

You can ignore the result:

line = Cocaine::CommandLine.new("noisy", "--extra-verbose", :swallow_stderr => true)
line.command # => "noisy --extra-verbose 2>/dev/null"

# ... and on Windows...
line.command # => "noisy --extra-verbose 2>NUL"

If your command errors, you get an exception:

line = Cocaine::CommandLine.new("git", "commit")
begin
  line.run
rescue Cocaine::ExitStatusError => e
  e.message # => "Command 'git commit' returned 1. Expected 0"
end

You don't have the command? You get an exception:

line = Cocaine::CommandLine.new("lolwut")
begin
  line.run
rescue Cocaine::CommandNotFoundError => e
  e # => the command isn't in the $PATH for this process.
end

But don't fear, you can specify where to look for the command:

Cocaine::CommandLine.path = "/opt/bin"
line = Cocaine::CommandLine.new("lolwut")
line.command # => "lolwut", but it looks in /opt/bin for it.

You can even give it a bunch of places to look:

    FileUtils.rm("/opt/bin/lolwut")
    `echo 'echo Hello' > /usr/local/bin/lolwut`
    Cocaine::CommandLine.path = ["/opt/bin", "/usr/local/bin"]
    line = Cocaine::CommandLine.new("lolwut")
    line.run # => prints 'Hello', because it searches the path

Or just put it in the command:

line = Cocaine::CommandLine.new("/opt/bin/lolwut")
line.command # => "/opt/bin/lolwut"

If your command might return something non-zero, and you expect that, it's cool:

line = Cocaine::CommandLine.new("/usr/bin/false", "", :expected_outcodes => [0, 1])
begin
  line.run
rescue Cocaine::ExitStatusError => e
  # => You never get here!
end

You can see what's getting run. The 'Command' part it logs is in green for visibility!

line = Cocaine::CommandLine.new("echo", ":var", :var => "LOL!", :logger => Logger.new(STDOUT))
line.run # => Logs this with #info -> Command :: echo 'LOL!'

But you don't have to, as you saw above where it doesn't use this. But you CAN log every command!

Cocaine::CommandLine.logger = Logger.new(STDOUT)
Cocaine::CommandLine.new("date").run # => Logs this -> Command :: date

POSIX Spawn

You can potentially increase performance by installing the posix-spawn gem (https://rubygems.org/gems/posix-spawn). This gem can keep your application's heap from being copied when forking command line processesG. For applications with large heaps the gain can be significant. To include posix-spawn, simply add it to your Gemfile or, if you don't use bundler, install the gem.

License

Copyright 2011 Jon Yurek and thoughtbot, inc. This is free software, and may be redistributed under the terms specified in the LICENSE file.