base-install-scripts/genfstab

#!/bin/bash

. ./common

shopt -s extglob

write_source() {
  local tag= spec= label= uuid= comment=()

  label=$(lsblk -rno LABEL "$1" 2>/dev/null)
  uuid=$(lsblk -rno UUID "$1" 2>/dev/null)

  if (( bylabel )); then
    tag=LABEL
    spec=$label
    comment=("$source" "UUID=$uuid")
  elif (( byuuid )); then
    tag=UUID
    spec=$uuid
    comment=("$source")
    if [[ $label ]]; then
      comment+=("LABEL=$label")
    fi
  else
    [[ $uuid ]] && comment+=("UUID=$uuid")
    [[ $label ]] && comment+=("LABEL=$label")
  fi

  [[ $comment ]] && printf '# %s\n' "${comment[*]}"

  if [[ $spec ]]; then
    printf '%-20s' "$tag=$spec"
  else
    printf '%-20s' "$source"
  fi
}

root=/mnt

while getopts ':LUr:' flag; do
  case $flag in
    L)
      bylabel=1
      ;;
    U)
      byuuid=1
      ;;
    r)
      # trim trailing slashes
      root=${OPTARG%%+(/)}
      ;;
    ?)
      die '%s: invalid option -- '\''%s'\' "${0##*/}" "$OPTARG"
      ;;
  esac
done
shift $(( OPTIND - 1 ))

if (( bylabel && byuuid )); then
  die "cannot specify both -U and -L"
fi

# handle block devices
findmnt -Recvruno SOURCE,TARGET,FSTYPE,VFS-OPTIONS "$root" |
    while read -r source target fstype opts; do
  # default 5th and 6th columns
  dump=0 pass=2

  # this is root
  target=${target#$root}
  if [[ $target = ?(/) ]]; then
    target=/
    pass=1
  fi

  # we don't fsck pseudofs
  if fstype_is_pseudofs "$fstype"; then
    pass=0
  fi

  # write one line
  write_source "$source"
  printf '\t%-10s' "$target" "$fstype" "$opts"
  printf '\t%s %s' "$dump" "$pass"
  printf '\n\n'
done

# handle swaps devices
{
  # ignore header
  read

  while read -r device _ _ _ prio; do
    options=defaults
    if [[ $prio != -1 ]]; then
      options+=,pri=$prio
    fi

    printf -v device '%b' "$device"

    printf '%-20s\t%-10s\t%-10s\t%-10s\t0 0\n' "$device" 'none' 'swap' "$options"
  done
} </proc/swaps

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