askenv -- sudo-esque method of temporarily setting environment variables

askenv.py

#!/usr/bin/env python

import sys, os
import getpass
import copy

if len(sys.argv) <3:
    print('usage: {0} =VARIABLE [=VARIABLE ...] CMD [ARGS ...]'.format(sys.argv[0]))
    print('Prompts for each VARIABLE in succession and executes CMD')
    sys.exit(1)

keepenv = ['HOME', 'PATH', 'TERM', 'USER', 'DISPLAY', 'LANG', 'PS1']

env = copy.deepcopy(os.environ)
for key in os.environ:
    if not key in keepenv:
        del env[key]

for i in range(len(sys.argv[1:])):
    if sys.argv[i+1][0] == '=':
        env[sys.argv[i+1][1:]] = getpass.getpass(sys.argv[i+1][1:] + ': ')
    else:
        os.execvpe(sys.argv[i+1], sys.argv[i+1:], env)

demo

[69] aiadicicco@sphinx askenv $ python askenv.py =FOO =BAR sh
FOO:
BAR:
[1] aiadicicco@sphinx askenv $ export
export BAR="this is bar"
export DISPLAY=":0.0"
export FOO="this is foo"
export HOME="/home/aiadicicco"
export LANG="en_US.UTF-8"
export OLDPWD
export PATH="/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
export PS1="\\[\\e[1m\\][\\#] \\u@\\h \\W \\\$ \\[\\e[0m\\]"
export PWD="/home/aiadicicco/work/sandbox/askenv"
export SHLVL="1"
export TERM="screen"
export USER="aiadicicco"
[2] aiadicicco@sphinx askenv $ exit
[70] aiadicicco@sphinx askenv $