executable 
Check if a file is executable using Node.js
Install
$ npm install --save executable
Usage
var executable = require('executable');
executable('bash', function (err, exec) {
console.log(exec);
//=> true
});
executable.sync('bash');
//=> true
CLI
$ npm install --global executable
$ executable --help
Usage
$ executable <file>
Example
$ executable optipng
License
MIT © Kevin Mårtensson