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rerun - run programs and restarts them on filesystem changes


Rerun launches your program, then watches the filesystem. If a relevant file changes, then it restarts your program.

Rerun works for both long-running processes (e.g. apps) and short-running ones (e.g. tests). It’s basically a no-frills command-line alternative to Guard, Shotgun, Autotest, etc. that doesn’t require config files and works on any command, not just Ruby programs.

Rerun’s advantage is its simple design. Since it uses exec and the standard Unix SIGINT and SIGKILL signals, you’re sure the restarted app is really acting just like it was when you ran it from the command line the first time.

By default it watches files ending in: rb,js,coffee,css,scss,sass,erb,html,haml,ru,yml,slim,md,feature,c,h. Use the --pattern option if you want to change this.

As of version 0.7.0, we use the Listen gem, which tries to use your OS’s built-in facilities for monitoring the filesystem, so CPU use is very light.

UPDATE: Now Rerun does work on Windows. Caveats: * not well-tested * after running, it may continue to slurp up some of your console input, so run it in a separate window, and/or use --background to disable on-the-fly commands, and/or press q to quit instead of CTRL-C * you may need to install the wdm gem manually: gem install wdm * You may see this persistent INFO error message; to remove it, use`--no-notify`: * INFO: Could not find files for the given pattern(s)


rerun [options] [--] cmd

For example, if you’re running a Sinatra app whose main file is app.rb:

rerun ruby app.rb

If the first part of the command is a .rb filename, then ruby is optional, so the above can also be accomplished like this:

rerun app.rb

Rails doesn’t automatically notice all config file changes, so you can force it to restart when you change a config file like this:

rerun --dir config rails s

Or if you’re using Thin to run a Rack app that’s configured in but you want it on port 4000 and in debug mode, and only want to watch the app and web subdirectories:

rerun --dir app,web -- thin start --debug --port=4000 -R

The -- is to separate rerun options from cmd options. You can also use a quoted string for the command, e.g.

rerun --dir app "thin start --debug --port=4000 -R"

Rackup can also be used to launch a Rack server, so let’s try that:

rerun -- rackup --port 4000

Want to mimic [autotest]( <> Try

rerun -x rake


rerun -cx rspec

And if you’re using [Spork]( <>) with Rails, you need to [restart your spork server]( <>) whenever certain Rails environment files change, so why not put this in your Rakefile...

desc "run spork (via rerun)"
task :spork do
  sh "rerun --pattern '{Gemfile,Gemfile.lock,spec/spec_helper.rb,.rspec,spec/factories/**,config/environment.rb,config/environments/test.rb,config/initializers/*.rb,lib/**/*.rb}' -- spork"

and start using rake spork to launch your spork server?

(If you’re using Guard instead of Rerun, check out [guard-spork]( <>) for a similar solution.)

How about regenerating your HTML files after every change to your [Erector]( <>) widgets?

rerun -x erector --to-html my_site.rb

Use Heroku Cedar? rerun is now compatible with foreman. Run all your Procfile processes locally and restart them all when necessary.

rerun foreman start


These options can be specified on the command line and/or inside a .rerun config file (see below).

--dir directory (or directories) to watch (default = "."). Separate multiple paths with ',' and/or use multiple -d options.

--pattern glob to match inside directory. This uses the Ruby Dir glob style — see <> for details. By default it watches files ending in: rb,js,coffee,css,scss,sass,erb,html,haml,ru,yml,slim,md,feature,c,h. On top of this, it also ignores dotfiles, .tmp files, and some other files and directories (like .git and log). Run rerun --help to see the actual list.

--ignore pattern file glob to ignore (can be set many times). To ignore a directory, you must append '/' e.g. --ignore 'coverage/'.

*On top of --pattern and --ignore, we ignore any changes to files and dirs starting with a dot.*

--signal (or -s) use specified signal(s) (instead of the default TERM,INT,KILL) to terminate the previous process. You can use a comma-delimited list if you want to try a signal, wait up to 5 seconds for the process to die, then try again with a different signal, and so on. This may be useful for forcing the respective process to terminate as quickly as possible. (--signal KILL is the equivalent of kill -9)

--wait sec (or -w) after asking the process to terminate, wait this long (in seconds) before either aborting, or trying the next signal in series. Default: 2 sec

--restart (or -r) expect process to restart itself, using signal HUP by default (e.g. -r -s INT will send a INT and then resume watching for changes)

--exit (or -x) expect the program to exit. With this option, rerun checks the return value; without it, rerun checks that the launched process is still running.

--clear (or -c) clear the screen before each run

--background (or -b) disable on-the-fly commands, allowing the process to be backgrounded

--notify NOTIFIER use growl or osx or notify-send for notifications (see below)

--no-notify disable notifications

--name set the app name (for display)

--force-polling use polling instead of a native filesystem scan (useful for Vagrant)

--quiet silences most messages

--verbose enables even more messages (unless you also specified --quiet, which overrides --verbose)

Also --version and --help, naturally.


If the current directory contains a file named .rerun, it will be parsed with the same rules as command-line arguments. Newlines are the same as any other whitespace, so you can stack options vertically, like this:

--pattern **/*.{rb,js,scss,sass,html,md}

Options specified on the command line will override those in the config file. You can negate boolean options with --no-, so for example, with the above config file, to re-enable logging, you could say:

rerun --no-quiet rackup

If you’re not sure what options are being overwritten, use --verbose and rerun will show you the final result of the parsing.


If you have growlnotify available on the PATH, it sends notifications to growl in addition to the console.

If you have terminal-notifier, it sends notifications to the OS X notification center in addition to the console.

If you have notify-send, it sends notifications to Freedesktop-compatible desktops in addition to the console.

If you have more than one available notification program, Rerun will pick one, or you can choose between them using --notify growl, --notify osx, --notify notify-send, etc.

If you have a notifier installed but don’t want rerun to use it, set the --no-notify option.

Download [growlnotify here]( <>) now that Growl has moved to the App Store.

Install [terminal-notifier]( <>) using gem install terminal-notifier. (You may have to put it in your system gemset and/or use sudo too.) Using Homebrew to install terminal-notifier is not recommended.

On Debian/Ubuntu, notify-send is availble in the libnotify-bin package. On other GNU/Linux systems, it might be in a package with a different name.


While the app is (re)running, you can make things happen by pressing keys:

r — restart (as if a file had changed)

f — force restart (stop and start)

c — clear the screen

x or q — exit (just like control-C)

p — pause/unpause filesystem watching

If you’re backgrounding or using Pry or a debugger, you might not want these keys to be trapped, so use the --background option.


The current algorithm for killing the process is:

•send [SIGTERM]( <>) (or the value of the --signal option)

•if that doesn’t work after 2 seconds, send SIGINT (aka control-C)

•if that doesn’t work after 2 more seconds, send SIGKILL (aka kill -9)

This seems like the most gentle and unixy way of doing things, but it does mean that if your program ignores SIGTERM, it takes an extra 2 to 4 seconds to restart.

If you want to use your own series of signals, use the --signal option. If you want to change the delay before attempting the next signal, use the --wait option.


If running inside a shared directory using Vagrant and VirtualBox, you must pass the --force-polling option. You may also have to pass some extra --ignore options too; otherwise each scan can take 10 or more seconds on directories with a large number of files or subdirectories underneath it.



Rerun will not pick up changes made to shared folders. This means that the common method of using Vagrant for an execution environment and using the /vagrant shared folder for source code will not work.

Instead, use [shotgun]( <>).


If you are using zsh as your shell, and you are specifying your --pattern as */.rb, you may face this error

Errno::EACCES: Permission denied - <filename>

This is because */.rb gets expanded into the command by zsh instead of passing it through to rerun. The solution is to simply quote ('' or "") the pattern. i.e

rerun -p **/*.rb rake test


rerun -p "**/*.rb" rake test