Could not find a JavaScript runtime

错误提示：

引用

I, [2012-09-04T08:52:02.594025 #3839]  INFO -- : listening on addr=0.0.0.0:3000 fd=5
I, [2012-09-04T08:52:02.594204 #3839]  INFO -- : worker=0 spawning...
I, [2012-09-04T08:52:02.594679 #3839]  INFO -- : master process ready
I, [2012-09-04T08:52:02.595505 #3841]  INFO -- : worker=0 spawned pid=3841
I, [2012-09-04T08:52:02.595856 #3841]  INFO -- : Refreshing Gem list
E, [2012-09-04T08:52:08.565301 #3841] ERROR -- : Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)

解决

#要么装上这俩gem
     gem 'execjs'
     gem 'therubyracer'
#要么nodejs编译
sudo aptitude install nodejs
#装不上，你就手动编译
$ git clone git://github.com/ry/node.git
$ cd node
$ ./configure
$ make
$ sudo make install