first commit

Readme.md

@@ -0,0 +1,47 @@
+NorthWatcher
+============
+
+NorthWatcher is cron for filesystem changes.
+
+Each line in your watch file specifies a directory to watch and a command to run when changes occur in that directory. You may optionally specify the kind of changes that will trigger the command.
+
+Lines that begin with # are comments. No trailing comments.
+
+The watch file resides at `~/.northwatcher` and looks like this:
+
+    # triggers when files are created or removed in /etc
+    /etc notify-the-admin.sh
+    
+    # triggerz when you save pikcherz of teh kittehz
+    + Pictures rbx post-to-twitter.rb
+    
+    # triggers when files are removed from the ~/todo directory
+    - todo update-remote-todo-list.sh
+
+So each line has an optional trigger followed by a directory and then a command. The triggers are:
+
+  * `+`: files are created
+  * `-`: files are removed
+
+You can use one or both of these, if you omit the trigger then both creations and removals are monitored.
+
+No frills.
+
+Potential Gotchas
+=================
+
+No spaces in filenames.
+
+If you actually want to watch `/etc` it seems like you need root privs. I don't need this behaviour so I'm not likely to fix it.
+
+Installation
+============
+
+Node nerd? It's just an `npm i --global northwatcher` away. Otherwise you'll need to [install node and npm](https://gist.github.com/579814) and then run the aforementioned command.
+
+Licensing
+=========
+
+Copyright 2011 Sami Samhuri
+
+MIT License

northwatcher.js

@@ -0,0 +1,189 @@
+// NorthWatcher by Sami Samhuri 2011 MIT
+//
+// TODO:
+//  - fork & run headless
+//  - watch .northwatcher and automatically reload changes, rolling back on errors
+//  - simple globbing
+//  - watching regular files for changes (simple case of globbing really)
+//  - support spaces in filenames (need a real parser instead of the regex stuff)
+//
+// Possible TODOs, may be out of scope:
+//  - watch files and/or directories for modifications
+//  - mail output to MAILTO
+//  - *maybe* a minimum interval at which commands are run, e.g. at most once every 5 minutes
+
+var fs = require('fs')
+
+function main() {
+  var path = require('path')
+    , eachLine = require('batteries').FileExt.eachLine
+    , rcFile = require('path').join(process.env.HOME, '.northwatcher')
+
+  fs.stat(rcFile, function(err, s) {
+    if (err) {
+      spiel()
+      return
+    }
+
+    eachLine(rcFile, function(line) {
+      // ignore comments and blank lines
+      if (line.match(/^\s*(#.*|)?$/)) {
+        console.log('>>> ignoring: "' + line + '"')
+        return
+      }
+
+      line = line.trim() // don't want to match \s* everywhere
+
+      // <trigger> <dir> <command>
+      var m
+      if (m = line.match(/^([-+]{0,2})\s*(\S+)\s*(.+)$/i)) {
+        var trigger = m[1] || '+-' // default watches for both
+          , dir = m[2]
+          , command = m[3]
+          , options = { create: trigger.indexOf('+') !== -1
+                      , remove: trigger.indexOf('-') !== -1
+                      , command: command
+                      }
+        if (dir.charAt(0) !== '/') dir = path.resolve(process.env.HOME, dir)
+        ensureDirectory(dir)
+        console.log('>>> watch line, trigger: ' + trigger + ', dir: ' + dir + ', command: ' + command)
+        watch(dir, options)
+      }
+
+      // if you're happy and you know it, syntax error!
+      else {
+        throw new Error('syntax error: ' + line)
+      }
+    })
+  })
+}
+
+function ensureDirectory(dir) {
+  var s
+  try {
+    s = fs.statSync(dir)
+  }
+  catch (e) {
+    throw new Error('directory does not exist: ' + dir)
+  }
+  if (!s.isDirectory()) {
+    throw new Error('not a directory: ' + dir)
+  }
+}
+
+var watchedDirs = {}
+  , files = {}
+
+function watch(dir, options) {
+  if (dir in watchedDirs) {
+    console.log('>>> first watcher for ' + dir)
+    watchedDirs[dir].push(options)
+  }
+  else {
+    console.log('>>> adding watcher for ' + dir)
+    watchedDirs[dir] = [options]
+    files[dir] = ls(dir)
+    fs.watchFile(dir, watcherForDir(dir, options))
+  }
+}
+
+function watcherForDir(dir, options) {
+  return function(curr, prev) {
+    // bail if no changes
+    if (curr.mtime <= prev.mtime) return
+    var newFiles = ls(dir)
+      , c = unset(setDiff(newFiles, files[dir]))
+      , r = unset(setDiff(files[dir], newFiles))
+    files[dir] = newFiles
+    console.log('>>> ' + dir + ' changed! c: ' + JSON.stringify(c) + ' r: ' + JSON.stringify(r))
+    watchedDirs[dir].forEach(function(o) {
+      if (c.length > 0 && o.create || r.length > 0 && o.remove) {
+        runCommand({ command: o.command
+                   , dir: dir
+                   , created: c
+                   , removed: r
+                   })
+      }
+    })
+  }
+}
+
+function runCommand(options) {
+  console.log('>>> running command: ' + options.command)
+  var spawn = require('child_process').spawn
+    // TODO quoting
+    , args = options.command.split(/\s+/)
+    , cmd = args.shift()
+  process.env.WATCH_DIR = options.dir
+  process.env.WATCH_CREATED = JSON.stringify(options.created)
+  process.env.WATCH_REMOVED = JSON.stringify(options.removed)
+  console.log('WATCH_DIR=' + process.env.WATCH_DIR)
+  console.log('WATCH_CREATED=' + process.env.WATCH_CREATED)
+  console.log('WATCH_REMOVED=' + process.env.WATCH_REMOVED)
+  console.log('cmd:  ' + cmd)
+  console.log('args: ' + args.join(' '))
+  spawn(cmd, args).stdout.on('data', function(x) {
+    console.log('child>>> ' + x)
+  })
+}
+
+function ls(dir) {
+  return set(fs.readdirSync(dir))
+}
+
+function set(elems) {
+  if (!Array.isArray(elems)) elems = [].slice.call(arguments)
+  return elems.reduce(function(set, x) {
+    set[x] = x
+    return set
+  }, {})
+}
+
+function unset(set) {
+  return Object.keys(set)
+}
+
+function setDiff(a, b) {
+  var d = {}
+    , x
+  for (x in a) if (!(x in b)) d[x] = a[x]
+  return d
+}
+
+function spiel() {
+  [ "NorthWatcher is cron for filesystem changes."
+  , ""
+  , "Each line in your watch file specifies a directory to watch and a"
+  , "command to run when changes occur in that directory. You may"
+  , "optionally specify the kind of changes that will trigger the"
+  , "command."
+  , ""
+  , "Lines that begin with # are comments. No trailing comments."
+  , ""
+  , "The watch file resides at `~/.northwatcher` and looks like this:"
+  , ""
+  , "    # triggers when files are created or removed in /etc"
+  , "    /etc notify-the-admin.sh"
+  , ""
+  , "    # triggerz when you save pikcherz of teh kittehz"
+  , "    + Pictures rbx post-to-twitter.rb"
+  , ""
+  , "    # triggers when files are removed from the ~/todo directory"
+  , "    - todo update-remote-todo-list.sh"
+  , ""
+  , "So each line has an optional trigger followed by a directory and"
+  , "then a command. The triggers are:"
+  , ""
+  , "    +  files are created"
+  , "    -  files are removed"
+  , ""
+  , "You can use one or both of these, if you omit the trigger then"
+  , "both creations and removals are monitored."
+  , ""
+  , "No frills."
+  , ""
+  , "Create a watch file and then run NorthWatcher again."
+  ].forEach(function(s) { console.log(s) })
+}
+
+if (require.main === module) main()

package.json

@@ -0,0 +1,23 @@
+{ "name" : "northwatcher"
+, "description" : "NorthWatcher is cron for filesystem changes."
+, "version" : "0.1"
+, "homepage" : "http://samhuri.net/proj/northwatcher"
+, "author" : "Sami Samhuri <sami.samhuri@gmail.com>"
+, "repository" :
+  { "type" : "git"
+  , "url" : "http://github.com/samsonjs/northwatcher.git"
+  }
+, "bugs" :
+  { "mail" : "sami.samhuri@gmail.com"
+  , "web" : "http://github.com/samsonjs/northwatcher/issues"
+  }
+, "bin" : { "northwatcher" : "./northwatcher.js" }
+, "main" : "./northwatcher.js"
+, "engines" : { "node" : ">=0.4.0" }
+, "licenses" :
+  [ { "type" : "MIT"
+    , "url" : "http://github.com/samsonjs/northwatcher/raw/master/LICENSE"
+    }
+  ]
+, "dependencies" : { "batteries" : "0.1.x" }
+}