set HOME and USER

forceenv.bash

# Try hard to set HOME and USER correctly.
# Supply a list of methods and try them until one is successful
function forceEnv {
        typeset -A methods
        until
                case ${1+_}${1-unset} in
                        ${methods[_$1]+*}) shift; continue ;;
                        unset) echo 'None of the supplied methods were successful.' >&2; return 1 ;;
                        _getent) getent passwd "${EUID:-$(id -u)}" | IFS=: read -r USER HOME{,,,,} SHELL ;;
                        _logname) USER=$(logname) && eval "HOME=~${USER}" ;;
                        _who) who -mT | IFS=' ' read -r USER _ && eval "HOME=~${USER}" ;;
                        *) printf -- 'Invalid method: %q\n' "$1" >&2
                esac

                [[ $? -eq 0 && $USER =~ ^[a-z_][a-z0-9_-]{0,31}[$]?$ && -d $HOME ]]
        do
                methods[_$1]=
                shift
        done
}

HOME= USER=
forceEnv getent logname who
echo "${HOME} ${USER} $?"