code: function run(exec, args, shell, callback) {
      var env = extend({}, this.env)
      env.TERM = 'dumb'
      const opts = { env: env, shell: shell }
  
      this.log.silly('execFile: exec = %j', exec)
      this.log.silly('execFile: args = %j', args)
      this.log.silly('execFile: opts = %j', opts)
      try {
        this.execFile(exec, args, opts, execFileCallback.bind(this))
      } catch (err) {
        this.log.silly('execFile: threw:\n%s', err.stack)
        return callback(err)
      }
  
      function execFileCallback(err, stdout, stderr) {
        this.log.silly('execFile result: err = %j', err && err.stack || err)
        this.log.silly('execFile result: stdout = %j', stdout)
        this.log.silly('execFile result: stderr = %j', stderr)
        if (err) {
          return callback(err)
        }
        const execPath = stdout.trim()
        callback(null, execPath)
      }
    }
docs: Run an executable or shell command, trimming the output.