将 JSON 解析为 shell 脚本中的数组
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Parse JSON to array in a shell script
提问by unconditionalcoder
I'm trying to parse a JSON object within a shell script into an array.
我正在尝试将 shell 脚本中的 JSON 对象解析为数组。
e.g.: [Amanda, 25, http://mywebsite.com]
例如：[阿曼达，25，http://mywebsite.com]
The JSON looks like:
JSON 看起来像：
{
"name" : "Amanda",
"age" : "25",
"websiteurl" : "http://mywebsite.com"
}
I do not want to use any libraries, it would be best if I could use a regular expression or grep. I have done:
我不想使用任何库，最好能使用正则表达式或 grep。我已经做好了：
myfile.json | grep name
This gives me "name" : "Amanda". I could do this in a loop for each line in the file, and add it to an array but I only need the right side and not the entire line.
这给了我“名字”：“阿曼达”。我可以在文件中的每一行循环中执行此操作，并将其添加到数组中，但我只需要右侧而不是整行。
回答by mklement0
If you really cannot use a proper JSON parser such as jq[1], try an awk-based solution:
如果您确实无法使用适当的 JSON 解析器，例如[1]，请尝试基于 - 的解决方案：jqawk
Bash 4.x:
重击 4.x：
readarray -t values < <(awk -F\" 'NF>=3 {print }' myfile.json)
Bash 3.x:
Bash 3.x：
IFS=$'\n' read -d '' -ra values < <(awk -F\" 'NF>=3 {print }' myfile.json)
This stores all property valuesin Bash array ${values[@]}, which you can inspect withdeclare -p values.
这将所有属性值存储在 Bash 数组中${values[@]}，您可以使用它进行检查declare -p values。
These solutions have limitations:
这些解决方案有局限性：
- each property must be on its own line,
- all values must be double-quoted,
- embedded escaped double quotes are not supported.
- 每个属性都必须在自己的行上，
- 所有值都必须用双引号引起来，
- 不支持嵌入的转义双引号。
All these limitations reinforce the recommendation to use a proper JSON parser.
所有这些限制都强化了使用适当 JSON 解析器的建议。
Note: The following alternative solutions use the Bash 4.x+ readarray -t valuescommand, but they also work with the Bash 3.x alternative, IFS=$'\n' read -d '' -ra values.
注意：以下替代解决方案使用 Bash 4.x+readarray -t values命令，但它们也适用于 Bash 3.x 替代方案IFS=$'\n' read -d '' -ra values.
grep+ cutcombination: A single grepcommand won't do (unless you use GNUgrep- see below), but adding cuthelps:
grep+cut组合：单个grep命令不起作用（除非您使用GNUgrep- 见下文），但添加cut帮助：
readarray -t values < <(grep '"' myfile.json | cut -d '"' -f4)
GNUgrep: Using -Pto support PCREs, which support \Kto drop everything matched so far (a more flexible alternative to a look-behind assertion) as well as look-ahead assertions ((?=...)):
GNUgrep：-P用于支持 PCRE，它支持\K删除迄今为止匹配的所有内容（后视断言的更灵活替代方案）以及前瞻断言 ((?=...))：
readarray -t values < <(grep -Po ':\s*"\K.+(?="\s*,?\s*$)' myfile.json)
Finally, here's a pure Bash (3.x+) solution:
最后，这是一个纯 Bash (3.x+) 解决方案：
What makes this a viable alternative in terms of performance is that no external utilities are called in each loop iteration; however, for larger input files, a solution based on external utilities will be much faster.
使其成为性能方面可行的替代方案的原因在于，在每次循环迭代中都不会调用任何外部实用程序；但是，对于较大的输入文件，基于外部实用程序的解决方案会快得多。
#!/usr/bin/env bash
declare -a values # declare the array
# Read each line and use regex parsing (with Bash's `=~` operator)
# to extract the value.
while read -r line; do
# Extract the value from between the double quotes
# and add it to the array.
[[ $line =~ :[[:blank:]]+\"(.*)\" ]] && values+=( "${BASH_REMATCH[1]}" )
done < myfile.json
declare -p values # print the array
[1] Here's what a robust jq-based solutionwould look like (Bash 4.x):readarray -t values < <(jq -r '.[]' myfile.json)
[1] 以下是基于强大jq的解决方案的样子（Bash 4.x）：readarray -t values < <(jq -r '.[]' myfile.json)
回答by Dr_Hope
jq is good enough to solve this problem
jq 足以解决这个问题
paste -s <(jq '.files[].name' YourJsonString) <(jq '.files[].age' YourJsonString) <( jq '.files[].websiteurl' YourJsonString)
So that you get a table and you can grep any rows or awk print any columns you want
这样你就可以得到一个表格，你可以 grep 任何行或 awk 打印你想要的任何列
回答by Dr_Hope
You can use a sed one liner to achieve this:
您可以使用 sed one liner 来实现此目的：
array=( $(sed -n "/{/,/}/{s/[^:]*:[[:blank:]]*//p;}" json ) )
Result:
结果：
$ echo ${array[@]}
"Amanda" "25" "http://mywebsite.com"
If you do not need/want the quotation marks then the following sed will do away with them:
如果您不需要/想要引号，那么以下 sed 将取消它们：
array=( $(sed -n '/{/,/}/{s/[^:]*:[^"]*"\([^"]*\).*//p;}' json) )
Result:
结果：
$ echo ${array[@]}
Amanda 25 http://mywebsite.com
It will also work if you have multiple entries, like
如果您有多个条目，它也将起作用，例如
$ cat json
{
"name" : "Amanda"
"age" : "25"
"websiteurl" : "http://mywebsite.com"
}
{
"name" : "samantha"
"age" : "31"
"websiteurl" : "http://anotherwebsite.org"
}
$ echo ${array[@]}
Amanda 25 http://mywebsite.com samantha 31 http://anotherwebsite.org
UPDATE:
更新：
As pointed out by mklement0 in the comments, there might be an issue if the file contains embedded whitespace, e.g., "name" : "Amanda lastname". In this case Amandaand lastnamewould both be read into seperate array fields each. To avoid this you can use readarray, e.g.,
正如 mklement0 在评论中指出的那样，如果文件包含嵌入的空格，例如"name" : "Amanda lastname". 在这种情况下，Amanda和lastname都将被读入单独的数组字段。为避免这种情况，您可以使用readarray，例如，
readarray -t array < <(sed -n '/{/,/}/{s/[^:]*:[^"]*"\([^"]*\).*//p;}' json2)
This will also take care of any globbing issues, also mentioned in the comments.
这也将处理评论中提到的任何通配问题。
