I write my scripts in python and run them with cmd by typing in:
C:\> python script.py
Some of my scripts contain separate algorithms and methods which are called based on a flag. Now I would like to pass the flag through cmd directly rather than having to go into the script and change the flag prior to run, I want something similar to:
C:\> python script.py -algorithm=2
I have read that people use sys.argv for almost similar purposes however reading the manuals and forums I couldn't understand how it works.
There are a few modules specialized in parsing command line arguments: getopt, optparse and argparse. optparse is deprecated, and getopt is less powerful than argparse, so I advise you to use the latter, it'll be more helpful in the long run.
Here's a short example:
import argparse
# Define the parser
parser = argparse.ArgumentParser(description='Short sample app')
# Declare an argument (`--algo`), saying that the
# corresponding value should be stored in the `algo`
# field, and using a default value if the argument
# isn't given
parser.add_argument('--algo', action="store", dest='algo', default=0)
# Now, parse the command line arguments and store the
# values in the `args` variable
args = parser.parse_args()
# Individual arguments can be accessed as attributes...
print args.algo
That should get you started. At worst, there's plenty of documentation available on line (say, this one for example)...