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Nand is a simple CLI tool to make anything daemon by Ruby. Nand is the meaning of Nandemo of Japanese.

Nandemo of here is a executable file and shell command, a non-executable Ruby file.

For starting daemonize TARGET, You can just type nand start TARGET. You can stop by nand stop TARGET. nand status TARGET show it running status.


Add this line to your application's Gemfile:

gem 'nand'

And then execute:

$ bundle

Or install it yourself as:

$ gem install nand

Easy Usage

Command Definition



$ cd /any/path
$ nand start sleep 1000
sleep is Start Success [85596]

You can start TARGET by start SUB_COMMAND. Though OPTION(s) after TARGET is Nand option, OPTION(s) Nand is unknown, will be handed over to TARGET. Here 1000 is handed over to sleep. And Nand recognizes a shell command sleep as TARGET name. When TARGET is success to be a daemon process, Nand show TARGET namd and daemon process id.


For the TARGET sleep running status, Nand status command show running status.

$ cd /any/path
$ nand status sleep
sleep is Running [85596] by USER in /any/path

You can omit the TARGET name sleep because you stay in /any/path.


Nand stop command stop daemon process with TARGET name.

$ nand stop sleep
sleep is Stopped [85596]
$ nand status sleep
sleep is Not Running in /any/path

You can also omit the TARGET name sleep as status because you stay in /any/path.

A Ruby File

Following forever_sleep.rb in current directory, you can make it daemon with file name as TARGET name.

require 'nand/plugin'

module Sample
  class ForeverSleep
    extend Plugin
    def self.executor(*argv)
    def exec
$ nand start forever_sleep.rb -p Sample::ForeverSleep
forever_sleep.rb is Start Success [86326]

$ nand stop forever_sleep.rb
forever_sleep.rb is Stopped [86326]

Nand can find the executor with exec method from defined class by -p option. The class need to extend Nand::Plugin. Then then executor can become a daemon process as TARGET name forever_sleep.rb.

More Usage

Avoid duplicated Nand Options

There are two ways to avoid duplicated Nand options for daemon's process options.

First, the options can be enclosed in "(double) or '(single) quatations.

$ nand start "--run_dir /tmp"

Others, you can put them after double dash(--).

$ nand start -- --run_dir /tmp

Pipes to Daemon Process

You can pipe to daemon process STDOUT and STDERR, STDIN by using Nand options --out and --err, --in.

Here is as follows:

sleep $1
echo $2

Then you can start with Nand pipe option.

$ nand start 100 '"foo bar baz"' --out out.log

$ cat out.log
foo bar baz

Running Directory

It is very important that you define the running directory with Nand option --run_dir. A PID file is put in the running directory and daemon process change the running directory. If you don't define the running directory, it is the current directory.

$ nand start 100 abc --run_dir /tmp --out out.log

Prohibition of Duplicated Start

Basically, you can not start duplicated daemon process name.

$ nand start sleep 1000
sleep is Start Success [97649]
$ nand start sleep 1000
sleep is Start Failed [PID file exist /any/path/]

If you would like to start duplicated daemon process name, you can start in another run directory or as another daemon process name.

$ nand start sleep 1000 --run_dir /tmp
sleep1 is Start Success [97611]
$ nand start sleep 1000 -n sleep1
sleep1 is Start Success [97649]
$ nand status -a
sleep is Running [97649] by USER in /run/dir
sleep1 is Running [97765] by USER in /run/dir
sleep is Running [97611] by USER in /tmp

Automatically Stop

Daemon process can automatically stop at the time limit, you defined.

$ nand start vmstat 5 --sec 600

Then vmstat will automatically stop after the lapse of 600 seconds.

Automatically Recovery

If you defined Nand -r option, when the daemon process downed, it would restart.

$ nand start sleep 100 -r

This sleep 100 will be down after 100 seconds, then sleep 100 will restart soon.


When nand stop, Nand send signal(SIGTERM) to daemon process group, and wait for termination of daemon process. Your daemon process finish by receiving a SIGTERM.

You must not remove a PID file for Nand .nand_[DAEMON_NAME].pid. It has be required to confirm integrity. If you removed it, Nand output an error. Then you need to stop the daemon process manually.


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request