結論
$ rackup -D
補足
ヘルプを見ましょう。ググるよりもまず公式です。
$ rackup --help
Usage: rackup [ruby options] [rack options] [rackup config]
Ruby options:
-e, --eval LINE evaluate a LINE of code
-b BUILDER_LINE, evaluate a BUILDER_LINE of code as a builder script
--builder
-d, --debug set debugging flags (set $DEBUG to true)
-w, --warn turn warnings on for your script
-q, --quiet turn off logging
-I, --include PATH specify $LOAD_PATH (may be used more than once)
-r, --require LIBRARY require the library, before executing your script
Rack options:
-s, --server SERVER serve using SERVER (thin/puma/webrick/mongrel)
-o, --host HOST listen on HOST (default: localhost)
-p, --port PORT use PORT (default: 9292)
-O NAME[=VALUE], pass VALUE to the server as option NAME. If no VALUE, sets it to true. Run '/home/takiya/sinatra-sidekiq/vendor/bundle/ruby/2.5.0/bin/rackup -s SERVER -h' to get a list of options for SERVER
--option
-E, --env ENVIRONMENT use ENVIRONMENT for defaults (default: development)
-D, --daemonize run daemonized in the background
-P, --pid FILE file to store PID
Common options:
-h, -?, --help Show this message
--version Show version
