如何在bash中循环jq唯一数组？

Question

我正在尝试遍历唯一名称并提交来自 github json 对象的消息。但是，当数组中有空格时，bash 会将它们视为单独的数组项

#!/usr/bin/env bash

commits='[
  {
    "author": {
      "email": "email@example.com",
      "name": "Chris",
      "username": "chris"
    },
    "committer": {
      "email": "email@example.com",
      "name": "Chris",
      "username": "chris"
    },
    "message": "commit message 1"
  },
  {
    "author": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "committer": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "message": "commit message 2"
  },
    {
    "author": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "committer": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "message": "commit message 3"
  }
]'

authors=$( jq -rc '[.[].author.name] | unique | @sh' <<<"${commits}" )
echo "authors: $authors"

# this works
for author in $authors
do
  echo "author: $author"
done

echo "------------"

# this does not
messages=$( jq -rc '[.[].message] | unique | @sh' <<<"${commits}" )
echo "messages: $messages"

for message in $messages
do
  echo "message: $message"
done

哪些输出

authors: 'Chris' 'John'
author: 'Chris'
author: 'John'
------------
messages: 'commit message 1' 'commit message 2' 'commit message 3'
message: 'commit
message: message
message: 1'
message: 'commit
message: message
message: 2'
message: 'commit
message: message
message: 3'

虽然我期望：

authors: 'Chris' 'John'
author: 'Chris'
author: 'John'
------------
messages: 'commit message 1' 'commit message 2' 'commit message 3'
message: 'commit message 1'
message: 'commit message 2'
message: 'commit message 3'

Answer 1

使用readarray(Bash 4+) 从jq以下位置映射空分隔的输出：

#!/usr/bin/env bash

commits='[
  {
    "author": {
      "email": "email@example.com",
      "name": "Chris",
      "username": "chris"
    },
    "committer": {
      "email": "email@example.com",
      "name": "Chris",
      "username": "chris"
    },
    "message": "commit message 1"
  },
  {
    "author": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "committer": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "message": "commit message 2"
  },
    {
    "author": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "committer": {
      "email": "email@example.com",
      "name": "John",
      "username": "jdoe"
    },
    "message": "commit message 3"
  }
]'

readarray -d '' authors < <(jq -j '.[].author.name + "\u0000"' <<<"${commits}")

for author in "${authors[@]}"
do
  echo "author: $author"
done

echo "------------"

readarray -d '' messages < <(jq -j '.[].message + "\u0000"' <<<"${commits}")

for message in "${messages[@]}"
do
  echo "message: $message"
done

或者，如果您有一个较旧的 Bash 版本，readarray或者mapfile您可以使用 ASCII 控制字符 ETX（TeXt 的结尾03）分隔字符串并使用read如下所示：

IFS=$'\03' read -d '' -ra authors < <(jq -j '.[].author.name + "\u0003"' <<<"${commits}")

IFS=$'\03' read -d '' -ra messages < <(jq -j '.[].message + "\u0003"' <<<"${commits}")

也可以通过一次jq调用来填充两个数组：

# Populates both arrays from a single jq call
{
  IFS=$'\03' read -r -d '' -a authors
  IFS=$'\03' read -r -d '' -a messages
} < <(jq -j '([.[].author.name] | unique | .[] + "\u0003"), "\u0000",  ([.[].message] | unique | .[] + "\u0003")' <<<"${commits}")

解释：

• [.[].author.name] | unique | .[] + "\u0003"：
  输出ETX (03)唯一作者姓名的分隔列表。

• "\u0000": 插入一个空分隔符

• [.[].message] | unique | .[] + "\u0003"：
  输出ETX (03)唯一消息的分隔列表。

• jq使用两个read命令将整个输出馈送到命令组。
  每个都read将停在空分隔符或流的末尾。

{
  IFS=$'\03' read -r -d '' -a authors
  IFS=$'\03' read -r -d '' -a messages
}