How to count items in JSON object using command line?

Question

I'm getting this kind of JSON reply from a curl command:

[
  {
    "cid": 49,
    "pyn": "yi4",
    "hans": "亿",
    "hant": "億",
    "tid": 68,
    "l10n": "cent million",
    "pid": 1,
    "pos": "num",
    "pos_txt": ""
  },
  {
    "cid": 50,
    "pyn": "yi4",
    "hans": "亿",
    "hant": "億",
    "tid": 69,
    "l10n": "100 millions",
    "pid": 1,
    "pos": "num",
    "pos_txt": ""
  }
]

How can I count the number of items in the array (here 2), using Bash or a command line (e.g. underscore) ?

Is JavaScript solution, okay for you?

thefourtheye
– thefourtheye

2014-01-24 13:51:01 +00:00
Commented Jan 24, 2014 at 13:51 — thefourtheye
– thefourtheye, Commented Jan 24, 2014 at 13:51
Through NPM module yes. Otherwise, no.

Édouard Lopez
– Édouard Lopez

2014-01-24 13:53:35 +00:00
Commented Jan 24, 2014 at 13:53 — Édouard Lopez
– Édouard Lopez, Commented Jan 24, 2014 at 13:53
Check my solution. That needs no npm. Plain JavaScript.

thefourtheye
– thefourtheye

2014-01-24 13:55:09 +00:00
Commented Jan 24, 2014 at 13:55 — thefourtheye
– thefourtheye, Commented Jan 24, 2014 at 13:55
I'm in a bash context, not web

Édouard Lopez
– Édouard Lopez

2014-01-24 13:59:41 +00:00
Commented Jan 24, 2014 at 13:59 — Édouard Lopez
– Édouard Lopez, Commented Jan 24, 2014 at 13:59

peak · Accepted Answer · 2018-09-25 19:59:10Z

743

Just throwing another solution in the mix...

Try jq, a lightweight and flexible command-line JSON processor:

jq length /tmp/test.json

Prints the length of the array of objects.

edited Sep 25, 2018 at 19:59

peak

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answered Jan 25, 2014 at 19:50

Ken

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7 Comments

Édouard Lopez Over a year ago

Your initial jq code (.[]) return the length of each object in the root array, while I'm looking for the length of the root array itself. Need to fix to .

Alex Bitek Over a year ago

If your root is not an array but an object with a key that contains an array, i.e. { "key": [elem1, elem2] } , then you can use use jq '.[] | length' file.json

Paulo Casaretto Over a year ago

Another useful option for that @MnemonicFlow is jq map_values(length) file.json . That will give you the keys as well.

hemflit Over a year ago

And if your input is made of independent objects instead of a single array, you'd use the -s or --slurp option, which collects them into an array while reading: jq -s length file.json

ssc Over a year ago

. | is not required, jq 'length' ... is enough

|

Mr. Lance E Sloan · Accepted Answer · 2021-07-16 17:47:48Z

129

You can also use jq to track down the array within the returned json and then pipe that in to a second jq call to get its length. Suppose it was in a property called records, like {"records":[...]}.

$ curl https://my-source-of-json.com/list | jq -r '.records | length'
2
$

edited Jul 16, 2021 at 17:47

Mr. Lance E Sloan

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answered Sep 21, 2020 at 19:23

yuvilio

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Comments

Édouard Lopez · Accepted Answer · 2016-03-31 11:21:36Z

96

The shortest expression is

curl 'http://…' | jq length

edited Mar 31, 2016 at 11:21

Édouard Lopez

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answered Mar 31, 2016 at 10:21

nikolay

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Comments

Dhruv Saraswat · Accepted Answer · 2021-08-24 07:10:54Z

32

If the JSON is being read from a file, try this -

number_of_objects=`jq '. | length' json_file_name.json`
echo $number_of_objects

If the JSON array is inside a key in the JSON as shown below -

{
  "fruits": [
    "apples",
    "oranges",
    "pears"
  ]
}

try this -

number_of_objects=`jq '.fruits | length' json_file_name.json`
echo $number_of_objects

(You'll have to download jq for this solution to work)

answered Aug 24, 2021 at 7:10

Dhruv Saraswat

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Comments

Kellen Stuart · Accepted Answer · 2023-02-21 20:42:45Z

20

Assume this structure:

(stored in a variable named json)

{
    "results": [
        { "id": 1 }
        { "id": 2 }
    ]

}

If you're looking to count how many are in the results array, the command is:

$json | jq '.results | length'

answered Feb 21, 2023 at 20:42

Kellen Stuart

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Comments

Édouard Lopez · Accepted Answer · 2014-01-24 14:45:22Z

5

A simple solution is to install jshon library :

jshon -l < /tmp/test.json
2

answered Jan 24, 2014 at 14:45

Édouard Lopez

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Comments

Benjamin Loison · Accepted Answer · 2023-08-16 22:00:28Z

2

try qic. it works like jq/jello. qic support interactive mode as well.

cat test.json | qic "len(_)"

https://walkerever.github.io/qic/

edited Aug 16, 2023 at 22:00

Benjamin Loison

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answered Jul 7, 2021 at 0:40

Y W

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