Simple file watcher. Monitors changes in filesystem by polling. No dependencies.

Needs Ruby and Rubygems:

$ [sudo] gem install filewatcher

Filewatcher scans filesystem and execute shell commands when files changes.

Usage:

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

Where

filename: filename(s) to scan.
shell command: shell command to execute when file changes on disk.

Run the echo command when the file myfile is changed:

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

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

> filewatcher *.js "node %FILENAME%"

In Linux/OSX:

$ filewatcher *.js "node $FILENAME"

Run the ruby script when it is changed:

$ filewatcher -e ruby-script.rb

Works with ruby, perl, python and awk by detecting file extensions.

Print a list of all files matching *.css first and the print filename when a file is beeing updated:

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

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

$ filewatcher *.js 'node $FILENAME'

The environment variables $FILEPATH and $FILEDIR 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

Examples:

Watch a list of files and directories:

require 'filewatcher'

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

Print the names of files beeing watched before we begin:

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

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

To detect if a file is updated 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 "New file: " + filename
  end
end

The Ruby API is fairly well tested but the command line program is buggy at the time beeing.

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.