不知道为什么会发生这种情况
'npm install -g compass'
它显示树确认安装。但我似乎无法检查指南针的版本。所以它可能存在也可能不存在，它存在于package.json文件中......无论如何这里是代码：
grunt serve
Running "serve" task
Running "clean:server" (clean) task
>> 0 paths cleaned.
Running "wiredep:app" (wiredep) task
Running "wiredep:test" (wiredep) task
Running "wiredep:sass" (wiredep) task
Running "concurrent:server" (concurrent) task
Warning: Running "compass:server" (compass) task
Warning: Command failed: /bin/sh -c compass --version
/bin/sh: compass: command not found
Use --force to continue.
Aborted due to warnings.
Execution Time (2015-12-04 20:10:42 UTC)
loading tasks 384ms ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 78%
loading grunt-contrib-compass 48ms ▇▇▇▇ 10%
compass:server 58ms ▇▇▇▇ 12%
Total 493ms Use --force to continue.
Aborted due to warnings.
Execution Time (2015-12-04 20:10:41 UTC)
loading tasks 338ms ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 16%
wiredep:app 320ms ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 15%
wiredep:test 27ms ▇▇ 1%
wiredep:sass 50ms ▇▇▇ 2%
concurrent:server 1.3s ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 63%