Simple filewatcher. Monitors changes in the filesystem by polling. Works everywhere.

The library is a single sourcefile with 83 lines of code, with no dependencies or platform specific code.

Needs Ruby and Rubygems:

$ [sudo] gem install filewatcher

Filewatcher scans the filesystem and execute shell commands when files are changed.

Usage:

filewatcher [-i interval] "<filename>" "<shell command>"

Where

filename: filename(s) to scan.
shell command: shell command to execute when a file is changed

Run the echo command when the file myfile is changed:

$ filewatcher "myfile" "echo 'myfile has changed'"

Run any javascript in the current directory when it is updated in Windows Powershell:

> filewatcher *.js "node %FILENAME%"

In Linux/OSX:

$ filewatcher *.js 'node $FILENAME'

Place filenames or filenames in quotes to use ruby filename globbing instead of shell filename globbing. This will make filewatcher look for files in subdirectories too.

> filewatcher "*.js" "node %FILENAME%"

In Linux/OSX:

> filewatcher '*.js' 'node $FILENAME'

Try to run the updated file as a script when it is updated by using the –exec/-e option. Works with files with file extensions that looks like a python, ruby, perl, php, javascript or awk script.

$ filewatcher -e *.rb

Print a list of all files matching *.css first and then output the filename when a file is beeing updated by using the –list/-l option:

$ filewatcher -l *.css 'echo file: $FILENAME'

Watch the “src” and “test” folders recursively, and run test when the filesystem gets updated:

$ filewatcher "src test" "ruby test/test_suite.rb"

The environment variable $FILENAME is available in the shell command argument. On unix like systems the command has to be enclosed in single quotes. To run node whenever a javascript file is updated:

$ filewatcher *.js 'node $FILENAME'

The environment variables $FILEPATH, $FILEDIR and $FSEVENT is also available.

--interval, -i <f>:   Interval in seconds to scan filesystem. Defaults to 0.5 seconds.
        --exec, -e:   Execute file as a script when file is updated.
 --recurse, -r <s>:   Recurse into the directory, watching everything matching 'expression'
 --include, -n <s>:   Include files (default: *)
 --exclude, -x <s>:   Exclude file(s) matching (default: "")
        --list, -l:   Print name of files being watched
     --version, -v:   Print version and exit
        --help, -h:   Show this message

Watch a list of files and directories:

require 'filewatcher'

FileWatcher.new(["lib/", "Rakefile"]).watch do |filename|
  puts "Updated " + filename
end

To detect if a file is updated, added or deleted:

FileWatcher.new(["README.rdoc"]).watch() do |filename, event|
  if(event == :changed)
    puts "File updated: " + filename
  end
  if(event == :delete)
    puts "File deleted: " + filename
  end
  if(event == :new)
    puts "Added file: " + filename
  end
end

To check for changes more often than the default once every second:

FileWatcher.new(["README.rdoc"]).watch(0.5) do |filename|
  puts "Updated " + filename
end

Print the names of the files found before watching files and folders:

FileWatcher.new(["lib/"],true).watch do |filename|
  puts "Updated " + filename
end
=> Watching files:
lib/filewatcher.rb

Use patterns to match filenames in current directory and subdirectories. The pattern is not a regular expression; instead it follows rules similar to shell filename globbing. Se Ruby documentation for syntax.

FileWatcher.new(["*.rb", "*.xml"]).watch do |filename|
  puts "Updated " + filename
end

The filewatcher library is just a single file with 96 LOC (including comments) with no dependencies.

The Ruby API is fairly well tested but the command line program has been buggy.

Code inspired by Tom Lieber’s blogg posting: alltom.com/pages/detecting-file-changes-with-ruby

Find method by c00lrguy: snippets.dzone.com/posts/show/5457

Globbing by Kristoffer Roupé github.com/kitofr

• Fork the project.

• Make your feature addition or bug fix.

• Add tests for it. This is important so I don’t break it in a future version unintentionally.

• Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but

  bump version in a commit by itself I can ignore when I pull)

• Send me a pull request. Bonus points for topic branches.

Copyright © 2011 - 2014 Thomas Flemming. See LICENSE for details.