[MiguelSanchez]

Here are a bunch of demo scripts, some practical, others useful as in introduction,
starting from the simplest:

Code

import sys #import the sys library
print(sys.argv) #prints the list argv

The above script, when run in Idle will simply return a list containing your script's filename.
However if run from command line, sys.argv will be a list where the first element is the filename and the remaining elements are the arguments from the command line.

With that in mind, the echo function in windows command line would look something like this.

Code

import sys #import the sys library
s="" #Create an empty string
for argument in sys.argv[1:]:#with every item in sys.argv except for the first
    s+=argument+" " #add the argument to the string, followed by a space
print(s) #prints the string

Or for those more familiar with handling strings, using the join function

Code

import sys #import the sys library
print(sys.argv[1:].join(" ")) #prints all the arguments joined together separated by a space, excluding the filenae

Getting the current working directory is possible wherever you call the script from.

Code

import os
print(os.getcwd())

Being on windows atm, I have this script in my "system environment variables" path so it can be called from any directory.

Finally, I'll take an intermission after concluding with something useful.
Being on windows it pained me to not have "curl";
The simplest method is

Code

from urllib.request import urlopen
import sys
site=sys.argv[1]#assign the first argument to the variable name "site"
myURL = urlopen(site)#open the site
print(myURL. read())#read the data from the site and print it to the active display

I'm going to take a break here and I'll comment a few more of my command line scripts to attach as a reply in the next 30 minutes.

---

Playing an audio file from command line
I hope I commented this well enough to be self-explainable.
It will require you to install pygame.
(run -> cmd -> "pip3 -install pygame")

Code

import pygame
import sys
from time import sleep
if len(sys.argv)>1:#if there is at least 1 argument (excluding filename)
    pygame.mixer.init() #initialise the pygame mixer
    my_sound = pygame.mixer.Sound(sys.argv[1])#Load the command line argument into the sound mixer
    seconds=my_sound.get_length()#assign the length of the sound to a variable called seconds
    my_sound.play()#play the sound
    sleep(seconds)#pause the program for the duration of the sound
    #end program
else:#if there isn't at least 1 argument (excluding filename)
    print("NO ARGUMENT")

---

Tuning.py (Produces a tone for tuning instruments)
Also requires pygame.
Usage:
tuning C2 // Plays note C2
tuning 322 // Plays the absolute pitch 332hz
tuning E5 436 // Plays the note E5 where A4 is tuned to 436HZ
tuning C3 432 // Plays the note C3 where A4 is tuned to 432HZ

Code

from __future__ import division
import pygame
import sys
from math import sin,pi
from time import sleep
def fold(List,Func,Arg):
    if List==[]:
        return Arg
    else:
        return fold(List[1:],Func,Func(Arg,List[0]))

def foldstr(Str,Func,Arg):
    if Str=="":
        return Arg
    else:
        return foldstr(Str[1:],Func,Func(Arg,Str[0]))
        

        
def displaymanual():
    print("""
Tuning:

Usage:
tuning C2 // Plays note C2
tuning 322 // Plays the absolute pitch 332hz
tuning E5 436 // Plays the note E5 where A4 is tuned to 436HZ
<Unimplemented>tuning E5 C4=260 // Plays the note E5 where C4 is tuned to 436Hz

""")

def playfreq(freq):
    pygame.mixer.init()
    my_sound = freqtosound(freq)
    my_sound.play()

def notetofreq(note,octave,rules="A4=440"):
    rules=rules.upper().strip()
    if rules[0:3]=="A4=":
        tuning=int(rules[3:])
        note=note[0].upper()+note[1:]
        ###49=A4=440hz Octave Starts on C and ends on B
        notes={"C":0,"C#":1,"D":2,"D#":3,"E":4,"F":5,"F#":6,"G":7,"G#":8,"A":9,"A#":10,"B":11}
        number=notes[note]+octave*12-8
        return tuning*2**((number-49)/12.0)
    else:
        tuning=int(rules[3:])
        centrenote=49-difference("A4",rules[:2])
        note=note[0].upper()+note[1:]
        ###49=A4=440hz Octave Starts on C and ends on B
        notes={"C":0,"C#":1,"D":2,"D#":3,"E":4,"F":5,"F#":6,"G":7,"G#":8,"A":9,"A#":10,"B":11}
        number=notes[note]+octave*12-8
        return tuning*2**((number-centrenote)/12.0)
        

def freqtosound(freq,samplerate=44100):
    import wave
    from struct import pack
    tempname="temp.wav"
    l=[(lambda a:abs(a)**2*(-1 if a<0 else 1))(sin(i/samplerate*freq*pi*2)) for i in range(samplerate*2)]
    f=wave.open(tempname, mode="wb")
    f.setparams((1, 4, 44100, 0, 'NONE', 'not compressed'))
    for i in l:
        frames=pack("<l",int(i*(2**30.9)))
        f.writeframesraw(frames)
    f.close()
    return pygame.mixer.Sound(tempname)

def isnote(a):
    a=a.upper()
    if isinstance(a,str):
        a=a.strip()
        if 'A' in a or 'B' in a or 'C' in a or 'D' in a or 'E' in a or 'F' in a or 'G' in a:
            return foldstr(a,lambda a,b: a and b in "ABCDEFG#123456789",True)
    else:
        return False
def isnumstr(a):
    if isinstance(a,str):
        a=a.strip()
        return foldstr(a,lambda a,b: a and b in "0123456789",True)
    else:
        return False
args=sys.argv[1:]
if len(args)==0:
    displaymanual()
if len(args)==1:
    if isnumstr(args[0]):
        playfreq(int(args[0]))
    elif isnote(args[0]):
        if args[0][-1:] in "0123456789":
            note=args[0][:-1]
            octave=int(args[0][-1:])
            playfreq(notetofreq(note,octave))
        else:
            note=args[0]
            octave=4
            playfreq(notetofreq(note,octave))
    else:
        displaymanual()
elif len(args)==2:
    if isnote(args[0]) and isnumstr(args[1]):#Plays the note E5 where A4 is tuned to 436HZ
        if args[0][-1:] in "0123456789":
            note=args[0][:-1]
            octave=int(args[0][-1:])
            playfreq(notetofreq(note,octave,"A4=%s"%args[1]))
        else:
            note=args[0]
            octave=4
            playfreq(notetofreq(note,octave,"A4=%s"%args[1]))

sleep(2)