How to get key names from JSON using jq

106k 2019-01-13 10:43

You can use:

$ jq 'keys' file.json

$ 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\n" ${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"

Ezhilan Mahalingam 1970-01-01 08:00:00

Thank you it worked! I am assigning these values into array in Shell script like array=($keyContents) but its not assigning properly, Is there any way to assign values to arrays mentioning delimiters?

Ezhilan Mahalingam 1970-01-01 08:00:00

Whenever the key/value has space in it, array is treating it as new value, I replaced spaces with _ which resolved the issue. Thank you very much! but now one more problem. : ( I am getting different orders when i get keys alone and when i get values alone : (

Niklas Holm 1970-01-01 08:00:00

Use mapfile -t arr < <(jq -r 'keys[]' ms.json) instead of that ugly process substitution to avoid having problems with spaces in the keys.

Niklas Holm 1970-01-01 08:00:00

@anubhava, if mapfile is unavailable a good old arr=(); while IFS='' read -r line; do arr+=("$line"); done < <(...) will also do.

Jeff Mercado 1970-01-01 08:00:00

Might want to mention keys_unsorted to get the keys in document order.