shell - How to get key names from JSON using jq

Question

curl http://testhost.test.com:8080/application/app/version | jq '.version' | jq '.[]'

The above command outputs only the values as below:

"[email protected]"

"2323"

"test"

"02-03-2014-13:41"

"application"

How can I get the key names instead like the below:

email

versionID

context

date

versionName

Answer 1

You can use:

jq 'keys' file.json

Complete example

$ cat file.json
{ "Archiver-Version" : "Plexus Archiver", "Build-Id" : "", "Build-Jdk" : "1.7.0_07", "Build-Number" : "", "Build-Tag" : "", "Built-By" : "cporter", "Created-By" : "Apache Maven", "Implementation-Title" : "northstar", "Implementation-Vendor-Id" : "com.test.testPack", "Implementation-Version" : "testBox", "Manifest-Version" : "1.0", "appname" : "testApp", "build-date" : "02-03-2014-13:41", "version" : "testBox" }

$ jq 'keys' file.json
[
  "Archiver-Version",
  "Build-Id",
  "Build-Jdk",
  "Build-Number",
  "Build-Tag",
  "Built-By",
  "Created-By",
  "Implementation-Title",
  "Implementation-Vendor-Id",
  "Implementation-Version",
  "Manifest-Version",
  "appname",
  "build-date",
  "version"
]

UPDATE: To create a BASH array using these keys:

Using BASH 4+:

mapfile -t arr < <(jq -r 'keys[]' ms.json)

On older BASH you can do:

arr=()
while IFS='' read -r line; do
   arr+=("$line")
done < <(jq 'keys[]' ms.json)

Then print it:

printf "%s
" ${arr[@]}

"Archiver-Version"
"Build-Id"
"Build-Jdk"
"Build-Number"
"Build-Tag"
"Built-By"
"Created-By"
"Implementation-Title"
"Implementation-Vendor-Id"
"Implementation-Version"
"Manifest-Version"
"appname"
"build-date"
"version"