#!/bin/bash
[ $# -eq 0 ] && {  # $# is number of args
  echo "$(basename $0): missing command" >&2
  exit 1
}
prog="$(which "$1")"  # see below
[ -z "$prog" ] && {
  echo "$(basename $0): unknown command: $1" >&2
  exit 1
}
shift  # remove $1, now $prog, from args
tty -s && exec </dev/null      # if stdin is a terminal, redirect from null
tty -s <&1 && exec >/dev/null  # if stdout is a terminal, redirect to null
tty -s <&2 && exec 2>&1        # stderr to stdout (which might not be null)
"$prog" "$@" &  # $@ is all args