device.sh

device_from_filename() {
  # canonicalize filename
  local realpath="$(readlink -e "$1")"

  [[ ! -e $realpath ]] && return 1

  # read /etc/mtab into associative array mtab
  local -A mtab
  local device mountpoint rest
  while read device mountpoint rest; do
    mtab[$mountpoint]="$device"
  done </etc/mtab

  # find mountpoint
  while [[ -n $realpath && -z ${mtab[$realpath]} ]]; do
    realpath="${realpath%/*}"
  done
  
  [[ -z $realpath ]] && realpath=/

  echo ${mtab[$realpath]}
  return 0
}