#!/bin/bash

# Sets a password environment variable

test "$#" -ge 1 || \

{ echo "Usage: . $0 env_var_name [msg] (note the initial \".\")" >&2; exit 2;}

msg="$2"

test -n "$msg" || msg="$1"

if test -z "${!1+t}"; then # env var with name $1 is unset

    read -s -p "Enter $msg password: "; echo

    export "$1"="$REPLY"

fi