使用bash读取json文件并从匹配的模式中grep字符串

Question

I am trying to parse below big json file using bash

//part of json file
{"name": "Jenkins", "version": "Jenkins-2.22"},
{"name": "FitNesse", "version": "FitNesse-2.1"},
{"name": "Quint","version": "Quint-2.12"},
{"name": "Otto","version": "Otto-1.0"},
{"name": "Gradle","version": "Gradle-1.1"}

I am able read the line matching 'version' from json file

while read line; do
  if [[ $line =~ "version" ]] ; then
    echo $line; fi
done < $manifestfile

I want to store the values[Jenkins-2.22, FitNesse-2.1, Quint-2.12, Otto-1.0, Gradle-1.1] in array in my while loop

need help with tweaking my above code

Answer 1

Assuming that the sample input above is inside a JSON array in file file.json , ie:

[
  {"name": "Jenkins", "version": "Jenkins-2.22"},
  {"name": "FitNesse", "version": "FitNesse-2.1"},
  {"name": "Quint","version": "Quint-2.12"},
  {"name": "Otto","version": "Otto-1.0"},
  {"name": "Gradle","version": "Gradle-1.1"}
]

^{Note: The only change required to make the commands below work in Bash 3.x too is to replace readarray -t versions with IFS=$'\\n' read -d '' -ra versions}

Using Bash 4.x and jq :

jq must be installed first, but that's well worth the effort, if feasible: it enables sophisticated, robust JSON parsing .

# Extract the version numbers and read them into a Bash array.
readarray -t versions < <(jq -r '.[].version' file.json)

# Print the array.
printf '%s\n' "${versions[@]}"

The above yields:

Jenkins-2.22
FitNesse-2.1
Quint-2.12
Otto-1.0
Gradle-1.1

---

Using Bash 4.x and awk :

If you cannot install jq , the following awk solution is an alternative, but note that it is much less robust and relies on the JSON to be formatted exactly as above .
This warning applies to any solution using standard utilities ( awk , grep , sed , ...) - only a dedicated JSON parser will work robustly .

readarray -t versions < <(awk -F\" 'NF>1 { print $(NF-1) }' file.json)

# Print the array.
printf '%s\n' "${versions[@]}"

Answer 2

sed -n 's/.*"\([^"]*\)"}.*/\1/p' <file>

Answer 3

jq is a proper tool to manipulate JSON data in Unix shell.

Let's say test.json file contains:

[
{"name": "Jenkins", "version": "Jenkins-2.22"},
{"name": "FitNesse", "version": "FitNesse-2.1"},
{"name": "Quint","version": "Quint-2.12"},
{"name": "Otto","version": "Otto-1.0"},
{"name": "Gradle","version": "Gradle-1.1"}
]

test_json.sh script (simplified version):

#!/bin/bash
versions=$(jq '.[] | .version' test.json)
versions_arr=($versions)  # contains an array of `version` key values

---

I must warn that the above approach ($versions) (creating an array upon string splitting) may fail if the string $versions has globbing characters in it.

---

The more "steady" approach would be using built-in read command with -a option to read the data wordwise into the specified array:

test_json.sh script ("steady" version):

#!/bin/bash
versions=$(jq '.[] | .version' test.json)
read -a versions_arr <<< $versions  # read `version` key values into array

Now, versions_arr is an array of version key values.
To print for eg the second array value you would do:

echo ${versions_arr[1]} 

The output:

"FitNesse-2.1"

Answer 4

Use JQ for parsing your Json easily, just install JQ, then use :

if you have a json array, and in every element you have the field version, you can use :

 cat myJsonFile | jq '.[].version'

That will return a list of versions

If you want to process line by line use

while read line; do
  if [[ $line =~ "version" ]] ; then
    echo $line | jq .[] | jq ."version" ; fi
done < $manifestfile