nodejs grunt子进程回调函数示例

Question

您是否可以帮助以下使用grunt运行的node exec命令示例？

echo命令正在执行，并且创建了hello-world.txt ，但回调函数中的grunt.log.writeln命令未触发。

var exec = require('child_process').exec,
    child;

    child = exec('echo hello, world! > hello-world.txt', 
        function(error, stdout, stderr){
            grunt.log.writeln('stdout: ' + stdout);
            grunt.log.writeln('stderr: ' + stderr);
            if (error !== null) {
                grunt.log.writeln('exec error: ' + error);
          }
        }
    );

参考文献：

http://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options

从节点子进程中检索值

Answer 1

DOH！ 这是在FAQ中。

将Gruntjs用于异步任务时，必须手动指定任务何时完成。 https://github.com/gruntjs/grunt/wiki/Frequently-Asked-Questions
https://github.com/robdodson/async-grunt-tasks
https://github.com/rwldrn/dmv/blob/master/node_modules/grunt/docs/api_task.md

对于后代，上面应该是这样的：

var exec = require('child_process').exec,
    child,
    done = grunt.task.current.async(); // Tells Grunt that an async task is complete

child = exec('echo hello, world! > hello-world.txt', 
    function(error, stdout, stderr){
        grunt.log.writeln('stdout: ' + stdout);
        grunt.log.writeln('stderr: ' + stderr);
        done(error); // Technique recommended on #grunt IRC channel. Tell Grunt asych function is finished. Pass error for logging; if operation completes successfully error will be null

      }
    }
);