Question

I have a script that goes using os.walk to go down a directory structure and matching files by extension and copies files to another location.

This is what i have for the file copy:

sourceDir=sys.argv[-2].rstrip("/")
destDir=sys.argv[-1].rstrip("/")
//copy code

So i would just call:

python mycode.py ~/a/ ~/b/ 

What i want to do is add an optional argument switch that will also match by a search pattern:

python mycode.py --match "pattern" ~/a/ ~/b/ 

In my code i would add this extra if:

if "--match" in sys.argvs:
  #try reference the string right after --match"
  for root, dir, files... etc

So to be precise, how can i find “pattern” if –“match” is in sys.argvs?
New to python, so any help would be greatly appreciated.

Thanks!

Answer 1

The argparse library is great at optional argument parsing:

import argparse

p = argparse.ArgumentParser(description="My great script")
p.add_argument("sourceDir", type=str, help="source directory")
p.add_argument("destDir", type=str, help="destination directory")
p.add_argument("--match", type=str, dest="match", help="search pattern")

args = p.parse_args()

print args.sourceDir, args.destDir, args.match

That way, args.match will be None if it’s not provided:

Davids-MacBook-Air:BarNone dgrtwo$ python mycode.py ~/a/ ~/b/
/Users/dgrtwo/a/ /Users/dgrtwo/b/ None
Davids-MacBook-Air:BarNone dgrtwo$ python mycode.py --match "pattern" ~/a/ ~/b/
/Users/dgrtwo/a/ /Users/dgrtwo/b/ pattern

It can also tell if there aren’t the right number of arguments:

usage: mycode.py [-h] [--match MATCH] sourceDir destDir
mycode.py: error: too few arguments

And includes a help message:

Davids-MacBook-Air:BarNone dgrtwo$ python mycode.py -h
usage: mycode.py [-h] [--match MATCH] sourceDir destDir

My great script

positional arguments:
  sourceDir      source directory
  destDir        destination directory

optional arguments:
  -h, --help     show this help message and exit
  --match MATCH  search pattern