Getopt: Using Environment Var To Override

[Tim Daneliuk]

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

try:
     opts, args = getopt.getopt(OPTIONS, 'your options go here')
except getopt.GetoptError:
     Usage()
     sys.exit(1)


-- 
------------------------------------------------------------------------------
Tim Daneliuk
tundra at tundraware.com