nodejs gruntsubprocesscallback函数的例子

你会好心帮助下面一个节点执行命令运行与咕噜的例子？

echo命令正在执行，并且创build了hello-world.txt ，但callback函数中的grunt.log.writeln命令不会触发。

 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subprocess中检索一个值

Answer 1

DOH！ 这是常见问题。

在使用Gruntjs进行asynchronous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 } } );