rc/sh/sv

#!/usr/bin/env sh
# YES_ZSH
# YES_BASH
# YES_DASH

sv() {
    [ $# -le 1 ] || { printf "%s\n" "$0: too many arguments" >&2; return 1; }
    awk "-F${1:- }" '
    NF>1{f[$1]=substr($0,length($1)+1+length(FS))}END{for(k in f)print k FS f[k]}
    '
}

[ "${SOURCING:-0}" -gt 0 ] || sv "$@"