Changing the split character for variable substitution

[joshlrogers]

Currently, the only character that is used for splitting an environment variable name to be used for variable substitution is the period. However, a period is not a valid character for an environment variable name in many *nix shells, including Bash. It would be very beneficial if we could override this separator or if it would split by either a period or an underscore (which is a valid character in an environment variable in all *nix shells).