NOTE: I neither use nor maintain this project anymore.

See https://github.com/cespare/reflex

This is a small guard plugin to run a command (typically a server) and restart it when files change. It restarts the process by killing it (with SIGINT, followed by SIGKILL if it doesn't die after a bit). It takes care of ensuring the process (and any children) are gone before bringing it up again.

$ gem install guard-restarter

or add it to your gemfile:

gem "guard-restarter"

Pretty straightforward:

guard :restarter, :command => "./run_server" do
  watch(/\.*\.[ch]$/)
end

You can also pass in the full set of arguments to Process.spawn for more control:

guard :restarter, :spawn => [{ "CC" => "gcc" }, "make", :err => "/dev/null"] do
  watch(/\.*\.[ch]$/)
end