Examples:
include Cinnabar::Command::ArrMixin
stdout = %w[printf World].run
stdout == "World"
include Cinnabar::Command::ArrMixin
fd, waiter = %w[ruby -e].push('sleep 2; puts "OK"').async_run
status = waiter.value
status.success?
output = fd.read.chomp
fd.close
output == 'OK'
async_run + wait_with_output
include Cinnabar::Command::ArrMixin
include Cinnabar::Command::TaskArrMixin
task = %w[ruby -e].push('sleep 2; puts "OK"').async_run
output, status = task.wait_with_output
status.success? output.chomp == 'OK'