process = ChildProcess.build("ruby", "-e", "sleep")

# inherit stdout/stderr from parent...
process.io.inherit!

# ...or pass an IO
process.io.stdout = Tempfile.new("child-output")

# modify the environment for the child
process.environment["a"] = "b"
process.environment["c"] = nil

# set the child's working directory
process.cwd = '/some/path'

# start the process
process.start

# check process status
process.alive?    #=> true
process.exited?   #=> false

# wait indefinitely for process to exit...
process.wait
process.exited?   #=> true

# get the exit code
process.exit_code #=> 0

# ...or poll for exit + force quit
begin
  process.poll_for_exit(10)
rescue ChildProcess::TimeoutError
  process.stop # tries increasingly harsher methods to kill the process.
end

r, w = IO.pipe

begin
  process = ChildProcess.build("sh" , "-c",
                               "for i in {1..3}; do echo $i; sleep 1; done")
  process.io.stdout = w
  process.start # This results in a subprocess inheriting the write end of the pipe.

  # Close parent's copy of the write end of the pipe so when the child
  # process closes its write end of the pipe the parent receives EOF when
  # attempting to read from it. If the parent leaves its write end open, it
  # will not detect EOF.
  w.close

  thread = Thread.new do
    begin
      loop do
        print r.readpartial(16384)
      end
    rescue EOFError
      # Child has closed the write end of the pipe
    end
  end

  process.wait
  thread.join
ensure
  r.close
end

process = ChildProcess.build("cat")

out      = Tempfile.new("duplex")
out.sync = true

process.io.stdout = process.io.stderr = out
process.duplex    = true # sets up pipe so process.io.stdin will be available after .start

process.start
process.io.stdin.puts "hello world"
process.io.stdin.close

process.poll_for_exit(exit_timeout_in_seconds)

out.rewind
out.read #=> "hello world\n"

search           = ChildProcess.build("grep", '-E', %w(redis memcached).join('|'))
search.duplex    = true # sets up pipe so search.io.stdin will be available after .start
search.io.stdout = $stdout
search.start

listing           = ChildProcess.build("ps", "aux")
listing.io.stdout = search.io.stdin
listing.start
listing.wait

search.io.stdin.close
search.wait

process = ChildProcess.build(*args)
process.leader = true
process.start

process = ChildProcess.build("sleep", "10")
process.detach = true
process.start

ChildProcess.build("cmd.exe", "/c", "bundle")
ChildProcess.build("ruby", "-S", "bundle")

logger = Logger.new('logfile.log')
logger.level = Logger::DEBUG
ChildProcess.logger = logger