如何从python脚本安装npm包？

Question

How to install npm package from a python script?

When I use subprocess.Popen(["node", "app.js"]) it is OK .
When I use subprocess.Popen(["npm", "install", "open"]) it is throwing an error .

Sorry, but Google and DuckDuckGo are not my friends today(

The main problem — automatic local installation required packages for my small utility because global packages are not working in windows.

PS. I have to ask this question because I'm trying to develop a plugin for Sublime Text 2.

This is the error in Sublime python console :

Reloading plugin …\stsync.py
Traceback (most recent call last):
  File ".\sublime_plugin.py", line 103, in create_application_commands
    cmds.append(class_())
  File ".\stsync.py", line 16, in __init__
  File ".\subprocess.py", line 633, in __init__
  File ".\subprocess.py", line 842, in _execute_child
WindowsError: [Error 2] 

line 16: subprocess.Popen(["node", "npm", "install", "open"])

---

If I change line 16 to subprocess.Popen(["node", "npm", "install", "open"]) then the python script will successfully invoke the nodejs terminal, but then it will fail with error:
cannot find npm module

Answer 1

将shell参数设置为True

subprocess.Popen(["node", "npm", "install", "open"], shell=True)

Answer 2

On Windows, many of the Node.js "binaries" are actually suffixed with the .cmd filename extension, which for whatever reason during the invocation through subprocess.Popen , it doesn't expand (even though PATHEXT might contain .cmd ).

So for a proper solution (that does not use shell=True ), try append .cmd to the Node.js binaries needed:

Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 25 2016, 22:01:18) [MSC v.1900 32 bit (In
tel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import subprocess
>>> subprocess.Popen(['npm.cmd', 'install'])
<subprocess.Popen object at 0x005E18B0>
>>> npm ERR! install Couldn't read dependencies

Of course it throws an error because I don't have a package.json in that directory. Try again using some other commonly used programs, such as webpack :

>>> subprocess.Popen(['webpack'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
...
FileNotFoundError: [WinError 2] The system cannot find the file specified

Oh right, add that .cmd :

>>> subprocess.Popen(['webpack.cmd'])
<subprocess.Popen object at 0x008A18B0>
>>> No configuration file found and no output filename configured via CLI option