update-repos.js

var fs = require('fs');
var spawn = require('child_process').spawn;

var summary = [];
var errors = [];

var app = {
  toProcess: 0,,
  processed: 0,
  readdir: function(err, files) {
    files.forEach(function(filename, i) {
      app.cd(filename, i, files.length);
    });
  },
  cd: function(filename, i, total) {
    fs.stat(filename, function(err, stats) {
      if ( stats.isDirectory() ) {
        if ( fs.existsSync(filename + '/.git') ) {
          app.toProcess++;
          app.updateRepos( __dirname + '/' + filename );
        }
      }
    });
  },
  updateRepos: function(workTree) {
    var added = false;
    var gitDir = workTree + '/.git';
    var fetch = spawn('git', ['--git-dir=' + gitDir, 'fetch']);

    fetch.on('exit', function(code) {
      if ( ! app.pushError(code, workTree + '(fetch) code: ' + code) ) {
        return;
      }
      var branch = spawn('git', ['--git-dir=' + gitDir, '--work-tree=' + workTree, 'branch']);

      var remote;
      branch.stdout.on('data', function(data) {
        data = data.toString();
        data = data.split(/\n/);
        data.forEach(function(line) {
          if ( line.match(/^\*/) ) {
            remote = line.replace('* ', 'origin/');
          }
        });
      });

      branch.on('exit', function(code) {
        if ( ! app.pushError(code, workTree + '(branch) code: ' + code) ) {
          return;
        }

        function runMerge() {
          if ( ! remote ) {
            setTimeout(runMerge, 100);
          } else {
            var merge = spawn('git', ['--git-dir=' + gitDir, '--work-tree=' + workTree, 'merge', remote]);
            merge.stdout.on('data', function(data) {
              data = data.toString();
              if ( ! added && ! data.match(/up-to-date/) ) {
                added = true;
                summary.push(workTree);
              }
            });

            merge.on('exit', function(code) {
              app.pushError(code, workTree + '(merge) code: ' + code, true);
            });
          }
        }

        runMerge();

      });

    })
  },
  pushError: function(code, message, finalProcess) {
    if ( code !== 0 ) {
      errors.push(message);
      finalProcess || app.processed++;
    }
    if ( finalProcess ) {
      app.processed++;
    }
    if(app.processed === app.toProcess) {
      app.summarize();
    }
    return code === 0;
  },
  summarize: function() {
    if ( ! summary.length && ! errors.length ) {
      console.log('Everything is up-to-date!\n');
    } else {
      if ( summary.length ) {
        console.log('These repos were updated\n-------------------------------------\n' + summary.join('\n'));
      }
      if ( errors.length ) {
        console.log('These repos had errors\n-------------------------------------\n' + errors.join('\n'));
      }
    }
    process.exit(0);
  }
};

fs.readdir('.', app.readdir);