Getopt: Using Environment Var To Override

Tim Daneliuk tundra at
Sat Jan 4 20:00:07 CET 2003

Skip Montanaro wrote:
>     Tim> I currently use getopt to process my command line args.  Is there
>     Tim> some standard/easy/idiomatic/Pythonic way to supplement this with
>     Tim> an environment variable?  
> None that I'm aware of, however depending on how your environment variable
> is formatted it might be trivial tack it onto the front or back of the args
> you pass to getopt.  Suppose you require your environment variable value to
> look like a set of arguments.  It could be as simple as
>     envargs = os.environ.get("MYENV")
>     if envargs is not None:
>         opts, args = getopt.getopt(envargs.split(), ...)
>     for opt, arg in opts:
>         ...
>     if args:
>         handle error?
> then later,
>     opts, args = getopt.getopt(sys.argv[1:], ...)
>     for opt, arg in opts:
>         ...
>     if args:
>         process parameters
> (Based upon the 1, 2, 3 you gave, I think you want to process environment
> variables before the command line.)
> Skip

In case anyone else cares, here's what I ended up with -
I use the program name (PROGNAME) as the environment
variable to hold the options in the same format as one
would use on the command line:

# Command line processing - Process any options set in the
# environment first, and then those given on the command line

OPTIONS = sys.argv[1:]
envopt = os.getenv(PROGNAME.upper())
if envopt:
     OPTIONS = envopt.split() + OPTIONS

     opts, args = getopt.getopt(OPTIONS, 'your options go here')
except getopt.GetoptError:

Tim Daneliuk
tundra at

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