在Python中从命令行输入变量

Question

What I want to do is very simple but I can't figure out a good and not too complex solution for this. Basically I want to define some global variables that will be used for example as a folder name

global folder = "C:\\TEMP\\" + foldername

And what I want is to set the foldername value as input when running the script, something like:

python myscript.py --folder somebeautifulfoldername

so when running my script, the folder will become C:\\TEMP\\somebeautifulfoldername

Answer 1

You can use the built-in argparse module for this combined with getting the command line arguments from sys.argv :

import argparse
import sys

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description = 'My script')
    parser.add_argument('--folder', help = "Subfolder of C:\TEMP\ to manipulate")
    args = parser.parse_args(sys.argv[1:])
    folder = "C:\\TEMP\\"+args.folder
    print folder

Here I added just a very simple argument with some basic help string, but you can do quite a lot with this like giving a default value, allowing a list of files instead of a single file, specify the type, ... . See the manual for more details and examples.

Usage:

>python myscript.py --folder somebeautifulfoldername
C:\TEMP\somebeautifulfoldername

>python myscript.py --help
usage: tmp.py [-h] [--folder FOLDER]

My script

optional arguments:
  -h, --help       show this help message and exit
  --folder FOLDER  Subfolder of C:\TEMP\ to manipulate

Answer 2

You can pass arguments to Python script like following:

python test.py arg1 arg2 arg3

And this is what you get

Argument List: ['test.py', 'arg1', 'arg2', 'arg3']

In your case:

python myscript.py somebeautifulfoldername

folder = "C:\\\\TEMP\\\\" + sys.argv[1]

Answer 3

import sys

folder = "none"
if("--folder" in  sys.argv):
    folder = sys.argv[sys.argv.index("--folder") + 1]        
print folder

If you run it the way you want:

python myscript.py --folder "HELLOFOLDER"

It will give: HELLOFOLDER

Answer 4

There are a number of options to parse command line arguments into a Python script. There's the standard library's optparse and argparse for instance.

A really nice 3rd party tool is docopt , which allows you to write the logic described above very easily by describing the script usage directly as documentation of your script like this:

"""My script

Usage:
  myscript.py --folder=<folder>

Options:
  -h --help             Show this screen.
  --version             Show version.
  --folder=<folder>     Choose folder.
"""

from docopt import docopt

if __name__ == '__main__':
    arguments = docopt(__doc__, version='myscript 1.0')
    folder = "C:\\TEMP\\" + arguments["--folder"]
    print(folder)

That said, you may also want to look into tempfile for generating temporary files to make the script more cross-platform. Hard-coding Windows-specific paths is rarely a good idea.