I did stackoverflow search and looked at Grunt API docs but couldn't find a way to run a parametrized task using grunt.task.run(taskname).

I have a simple task which accepts a parameter and prints the message on console:

grunt.registerTask('hello', 'greeting task', function(name) {

   if(!name || !name.length)

        grunt.warn('you need to provide a name');



    console.log('hello ' + name + '!');



});

I call the above task using below task which validates the task and if task exists then it runs it:

 grunt.registerTask('validateandruntask', 'if task available then run given  task', function(taskname) {

       if(!taskname || !taskname.length) {

           grunt.warn('task name is needed to run this task');

       }



    if(!grunt.task.exists(taskname)) {

        grunt.log.writeln('this task does not exist!');

    } else {

        grunt.log.writeln(taskname + ' exists. Going to run this task');

        grunt.task.run(taskname);

    }



});

Now from command line, I am passing 'hello' task as parameter to 'validateandruntask' but I am not been able to pass the parameter to 'hello' task from command line:

This is what I tried on command line but it didn't work:

grunt validateandruntask:hello=foo

grunt validateandruntask:hello:param=name

First thing, the way to pass an arg through the command line is to use :.
For example to call hello directly:

grunt hello:you

To call it with multiple arguments, just separate them by :, like

grunt hello:mister:president

And to use these multiple arguments in the task, you do the same as plain Javascript: use arguments (all details here):

grunt.registerTask('hello', 'greeting task', function(name) {

  if(!name || !name.length)

    grunt.warn('you need to provide a name');

  // unfortunately arguments is not an array,

  // we need to convert it to use array methods like join()

  var args = Array.prototype.slice.call(arguments);

  var greet = 'hello ' + args.join(' ') + '!';

  console.log(greet);

});

Then you want to call grunt validateandruntask:hello:mister:president, and modify your code to handle the variable parameters as well:

grunt.registerTask('validateandruntask', 'if task available then run given  task', function(taskname) {

   if(!taskname || !taskname.length) {

       grunt.fail.fatal('task name is needed to run this task');

   }



  var taskToCall = taskname;

  for(var i = 1; i < arguments.length; i++) {

    taskToCall += ':' + arguments[i];

  }

  console.log(taskToCall);



  if(!grunt.task.exists(taskname)) {

      grunt.log.writeln('this task does not exist!');

  } else {

      grunt.log.writeln(taskname + ' exists. Going to run this task');

      grunt.task.run(taskToCall);

  }

});