Please replace [...] with your code snippets. This script will be used in busybox to find out the partitions by following the specific order.

list.sh

#!/bin/sh

PARTITIONS="/dev/mmcblk0p1 /dev/mmcblk1p1 /dev/nvm0n1p1 /dev/nvm0n2p1 /dev/sda1 /dev/sdb1"
DEVICES="/dev/sdb /dev/nvm0n2 /dev/nvm0n1 /dev/mmcblk0"

result=""

[...] # can not use PARTITIONS here

for partition in $PARTITIONS; do
  [...]
done

[...] # can not use PARTITIONS here

# Expected result: /dev/sdb1 /dev/nvm0n2p1 /dev/nvm0n1p1 /dev/mmcblk0p1
echo $result

我想到的是這樣

candidates=""

for partition in $PARTITIONS; do
  for device in $DEVICES; do
    case "$partition" in
      $device*)
        candidates="$candidates $partition"
        ;;
    esac
  done
done

for device in $DEVICES; do
  for candidate in $candidates; do
    case "$candidate" in
      $device*)
        if [ -z "$result" ]; then
          result="$candidate"
        else
          result="$result $candidate"
        fi
        ;;
    esac
  done
done

另一個更簡單的版本，雖然無法直接存取 PARTITIONS 的值，但是可以先用另一個變數存起來之後再使用。 XD

candidates=""

for partition in $PARTITIONS; do
  if [ -z "$candidates" ]; then
    candidates="$partition"                
  else
    candidates="$candidates $partition"
  fi
done

for device in $DEVICES; do
  for candidate in $candidates; do
    case "$candidate" in
      $device*)
        if [ -z "$result" ]; then
                result="$candidate"
        else
                result="$result $candidate"
        fi
        ;;
    esac
  done
done