Referrer key missing form os.environ dictionary?

[Chris Angelico]

On Fri, Sep 27, 2013 at 12:11 AM, Grant Edwards <invalid at invalid.invalid> wrote:
> On a Unix system when you invoke a program, you "pass" it four things:
>
>  1) A dictionary where keys/values are both strings [enviornment variables]
>  2) A list of strings [command line args]
>  3) A set of open file descriptors.
>  4) The current working directory.
>
> You can provide input values to the program through any of these.
>
> For interactive programs, 2 and 3 are the most convenient.

Hrm, not sure about #3 for interactive programs, unless you
specifically mean the three standard streams. With most Unix shells,
you should be able to set environment variables:

PGUSER=fred PGPASSWORD=secret psql

Not as convenient as #2, but far easier than passing an open file
descriptor. Of course, passing file descriptors around is pretty easy
programmatically, but when you say "interactive" I assume you're
talking also about an interactive shell.

GUI interactions of course follow their own rules completely. In most
systems, it's really easy to invoke an application with one argument,
a file name; it's generally much harder to customize the arguments at
the keyboard. OS/2 had a facility for doing that. You just put square
brackets into the configured args and it'd turn it into a prompt:

--foo=bar --mode=[Choose mode, 1-3:] %*

You'd get a nice little popup with the prompt you specified, and
whatever you type gets put into the args. Haven't seen that in any
other system - at least, not as conveniently.

ChrisA