I use python to create my project settings setup, but I need help getting the command line arguments.
I tried this on the terminal:
$python myfile.py var1 var2 var3
In my Python file, I want to use all variables that are input.
This question is related to
python
command-line
First, You will need to import sys
sys - System-specific parameters and functions
This module provides access to certain variables used and maintained by the interpreter, and to functions that interact strongly with the interpreter. This module is still available. I will edit this post in case this module is not working anymore.
And then, you can print the numbers of arguments or what you want here, the list of arguments.
Follow the script below :
#!/usr/bin/python
import sys
print 'Number of arguments entered :' len(sys.argv)
print 'Your argument list :' str(sys.argv)
Then, run your python script :
$ python arguments_List.py chocolate milk hot_Chocolate
And you will have the result that you were asking :
Number of arguments entered : 4
Your argument list : ['arguments_List.py', 'chocolate', 'milk', 'hot_Chocolate']
Hope that helped someone.
If you call it like this: $ python myfile.py var1 var2 var3
import sys
var1 = sys.argv[1]
var2 = sys.argv[2]
var3 = sys.argv[3]
Similar to arrays you also have sys.argv[0]
which is always the current working directory.
You can use sys.argv
to get the arguments as a list.
If you need to access individual elements, you can use
sys.argv[i]
where i
is index, 0
will give you the python filename being executed. Any index after that are the arguments passed.
Some additional things that I can think of.
As @allsyed said sys.argv gives a list of components (including program name), so if you want to know the number of elements passed through command line you can use len() to determine it. Based on this, you can design exception/error messages if user didn't pass specific number of parameters.
Also if you looking for a better way to handle command line arguments, I would suggest you look at https://docs.python.org/2/howto/argparse.html
import sys
sys.argv[1:]
will give you a list of arguments (not including the name of the python file)
Python code:
import sys
# main
param_1= sys.argv[1]
param_2= sys.argv[2]
param_3= sys.argv[3]
print 'Params=', param_1, param_2, param_3
Invocation:
$python myfile.py var1 var2 var3
Output:
Params= var1 var2 var3
I highly recommend argparse
which comes with Python 2.7 and later.
The argparse
module reduces boiler plate code and makes your code more robust, because the module handles all standard use cases (including subcommands), generates the help and usage for you, checks and sanitize the user input - all stuff you have to worry about when you are using sys.argv
approach. And it is for free (built-in).
Here a small example:
import argparse
parser = argparse.ArgumentParser("simple_example")
parser.add_argument("counter", help="An integer will be increased by 1 and printed.", type=int)
args = parser.parse_args()
print(args.counter + 1)
and the output for python prog.py -h
usage: simple_example [-h] counter
positional arguments:
counter counter will be increased by 1 and printed.
optional arguments:
-h, --help show this help message and exit
and for python prog.py 1
as you would expect:
2
Source: Stackoverflow.com