如何在bash中创建列表(或类似列表)的数组? [英] How can I make an array of lists (or similar) in bash?

问题描述

我想遍历bash中的一些列表.现在我有

I want to iterate over a few lists in bash. Right now I have

array=("list1item1 list1item2" "list2item list2item2")

for list in "${array[@]}"
do
    for item in $list
    do
        echo $item
    done
done

这不起作用.有什么方法可以在bash中创建列表列表，数组数组或列表数组?

This doesn't work. Is there any way to make a list of lists, array of arrays, or array of lists in bash?

我想遍历list1，然后遍历list1中的listitems.然后遍历list2和list2中的列表项.

I want to iterate over list1, then the listitems in list1. Then iterate over list2, and the list items in list2.

推荐答案

我将缺少的do和done添加到您的代码中

Once I added the missing do and done into your code:

array=("list1item1 list1item2" "list2item list2item2")

for list in "${array[@]}"
do
    for item in $list
    do
        echo $item
    done
done

它产生了预期的输出:

list1item1
list1item2
list2item
list2item2

我不清楚这与您的期望有何不同.

It's not clear to me how this differs from your expectation.

但是，这不是将列表嵌套到数组中的一种非常通用的方法，因为它取决于内部列表是由IFS分隔的. Bash不提供嵌套数组.数组严格来说是字符串数组，仅此而已.

However, that is not a very general way of nesting a list into an array, since it depends on the internal list being IFS-separated. Bash does not offer nested arrays; an array is strictly an array of strings, and nothing else.

您可以使用间接寻址(${!v})并将变量名称存储到外部数组中，尽管这有点难看.下面是一个不太丑陋的变体，它依赖于namerefs.它将与相当近期的bash版本一起使用:

You can use indirection (${!v}) and store variable names into your outer array, although it is a bit ugly. A less ugly variant is the following, which relies on namerefs; it will work with reasonably recent bash versions:

array=(list1 list2)
list1=("list 1 item 1" "list 1 item 2")
list2=("list 2 item 1" "list 2 item 2")
for name in "${array[@]}"; do
  declare -n list=$name
  for item in ${list[@]}; do
    echo "$item"
  done
done

输出:

list 1 item 1
list 1 item 2
list 2 item 1
list 2 item 2

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