Run your shell command whenever any file is updated.

grunt-exec-php.js

'use strict';

/**
 *
 * Make sure you must install modules below before use.
 *
 * > $ npm i grunt-contrib-watch --save-dev
 * > $ npm i grunt-exec --save-dev
 *
 *
 */


module.exports = function(grunt) {

    // Import modules from package.json's devDependencies
    var taskName;
    var pkg = grunt.file.readJSON('package.json');
    for (taskName in pkg.devDependencies) {
        if (taskName.substring(0, 6) == 'grunt-') {
          grunt.loadNpmTasks(taskName);
        }
      }

    grunt.initConfig({
        watch: {
            files: ['**/*'],
            tasks: ['phptest'],
            options: {
                spawn: false,
            },
        },
        exec: {
          list_files: {
            // do shell command what you want
            command: 'ls -l',
            stdout: true
          }
        }
    });

    grunt.registerTask('default', ['watch']);
    grunt.registerTask('phptest', ['exec']);
};