ls和-lh / usr在NodeJ中是什么意思？

Question

在NodeJs中使用子进程模块时， ls和-lh/usr代表什么？

Answer 1

If you're referring to the example for spawn() :

var spawn = require('child_process').spawn,
    ls    = spawn('ls', ['-lh', '/usr']);

// ...

ls is, from left to right:

• A variable referring to the ChildProcess instance created and returned by spawn() .
• The name of a common unix/linux command for listing the contents of a directory .

The snippet is equivalent to executing the following command in a shell/terminal, where spaces separate the command and arguments:

ls -lh /usr

Which will try to list the contents of the /usr directory, specifying -lh as 2 combined options to output in " long listing format " ( -l ) with " human readable sizes " ( -h ).

It assumes the system running the code has a compatible ls command or executable.