sys.argv[1] meaning in script

Question

I\'m currently teaching myself Python and was just wondering (In reference to my example below) in simplified terms what the sys.argv[1] represents. Is it simpl

Answer 1

sys.argv is a attribute of the sys module. It says the arguments passed into the file in the command line. sys.argv[0] catches the directory where the file is located. sys.argv[1] returns the first argument passed in the command line. Think like we have a example.py file.

example.py

import sys # Importing the main sys module to catch the arguments
print(sys.argv[1]) # Printing the first argument

Now here in the command prompt when we do this:

python example.py

It will throw a index error at line 2. Cause there is no argument passed yet. You can see the length of the arguments passed by user using if len(sys.argv) >= 1: # Code. If we run the example.py with passing a argument

python example.py args

It prints:

args

Because it was the first arguement! Let's say we have made it a executable file using PyInstaller. We would do this:

example argumentpassed

It prints:

argumentpassed

It's really helpful when you are making a command in the terminal. First check the length of the arguments. If no arguments passed, do the help text.

Answer 2

To pass arguments to your python script while running a script via command line

python create_thumbnail.py test1.jpg test2.jpg

here, script name - create_thumbnail.py, argument 1 - test1.jpg, argument 2 - test2.jpg

With in the create_thumbnail.py script i use

sys.argv[1:]

which give me the list of arguments i passed in command line as ['test1.jpg', 'test2.jpg']

Answer 3

sys .argv will display the command line args passed when running a script or you can say sys.argv will store the command line arguments passed in python while running from terminal.

Just try this:

import sys
print sys.argv

argv stores all the arguments passed in a python list. The above will print all arguments passed will running the script.

Now try this running your filename.py like this:

python filename.py example example1

this will print 3 arguments in a list.

sys.argv[0] #is the first argument passed, which is basically the filename. 

Similarly, argv1 is the first argument passed, in this case 'example'

A similar question has been asked already here btw. Hope this helps!