Can I pass a string variable to jq not the file?

Question

I want to convert JSON string into an array in bash. The JSON string is passed to the bash script as an argument (it doesn't exist in a file).

Is there a way of achieving it without using some temp files?

Similarly to this:

script.sh

#! /bin/bash
json_data='{"key":"value"}'
jq '.key' $json_data

jq: error: Could not open file {key:value}: No such file or directory

score 169 · Accepted Answer · answered Nov 03 '17 at 23:36

169

I would suggest using a bash here string. e.g.

jq '.key' <<< "$json_data"

answered Nov 03 '17 at 23:36

jq170727

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How would I use two strings instead of two files so I can use `jq -s '.[0] * .[1]' file1 file2` ? – Katie Dec 05 '18 at 00:35
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@KatieS: Use a new bash variable to concatenate the two strings, then pass that. – MSalters May 02 '19 at 12:58
and how do you pipe the results of that into something else? – CpILL Nov 11 '20 at 05:29
Perhaps `jq '.key' <<< "$json_data" | something else` – jq170727 Nov 13 '20 at 00:44
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I think this one is an easier to understand syntax: `echo "$json_data" | jq '.key'` – Alex Mar 10 '23 at 10:29

score 39 · Answer 2 · edited Jun 20 '20 at 09:12

39

The value of the variable "json_data" that was given in the original question was not valid JSON, so this response still covers both cases (nearly-valid and valid JSON).

Valid JSON

If "$json_data" does hold a valid JSON value, then here are two alternatives not mentioned elsewhere on this page.

`--argjson`

For example:

 jq -n --argjson data "$json_data" '$data.key'

`env`

If the shell variable is not aleady an environment variable:

json_data="$json_data" jq -n 'env.json_data | fromjson.key'

Nearly-valid JSON

If indeed $json_data is invalid as JSON but valid as a jq expression, then you could adopt the tactic illustrated by the following transcript:

$ json_data='{key:"value"}'
$ jq -n "$json_data" | jq .key
"value"

edited Jun 20 '20 at 09:12

Community

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answered Nov 04 '17 at 00:33

peak

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I meant the 'key' to be the string type. Should probably have used the 'name' word instead. – Maciek Rek Nov 04 '17 at 08:47
Anyways both examples worked for me (bash on mac), even with quoted "key" and produced similar results to the here string from the jq170727's solution. – Maciek Rek Nov 04 '17 at 09:11
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For anyone else who doesn't need the key search: it's just `jq -n $json_data`. So simple, but both the docs and online examples are super unclear for such a simple scenario. They all seem to assume you want to do something complicated. – Mike B Jan 06 '21 at 02:46

score 21 · Answer 3 · edited Nov 03 '17 at 23:46

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Use the bash: echo "$json_data" | jq '.key'

edited Nov 03 '17 at 23:46

peak

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answered Nov 03 '17 at 22:59

Javier

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score 12 · Answer 4 · answered Nov 03 '17 at 22:59

12

Absolutely. Just tell bash to give it a file instead.

jq '.key' <(echo "$json_data")

And make sure you run it in bash, not sh.

answered Nov 03 '17 at 22:59

Ignacio Vazquez-Abrams

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score 8 · Answer 5 · answered Nov 28 '19 at 03:32

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If you want to use inline command, I found this work on my Mac:

echo '{"key":"value"}' | jq .key

answered Nov 28 '19 at 03:32

Abigail Nguyen

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Store the result in a variable to use in later stages. Say your json is already in a variable and you need the result in another one. `jsonData="{"key":"value"}" result=$(echo $jsonData | jq -r '.key')` echo $result will produce value as result. – Gaurav Dalal Jul 02 '20 at 07:49

score 5 · Answer 6 · edited Jan 10 '19 at 07:50

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#! /bin/bash
json_data='{"key":"value"}'
echo $json_data | jq --raw-output '.key'

edited Jan 10 '19 at 07:50

taras

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answered Jan 10 '19 at 05:51

Supun Madushanka

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score 2 · Answer 7 · answered Jun 07 '18 at 23:44

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If you're trying to do this in a .sh file, this is what worked for me:

local json_data $(getJiraIssue "$1")               # store JSON in var
echo `jq -n "$json_data" | jq '.fields.summary'`   # pass that JSON var to jq

answered Jun 07 '18 at 23:44

Wesley Smith

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score -2 · Answer 8 · answered Apr 15 '22 at 08:23

-2

Just do

$ jq '.key' <<< $'{"key":"value"}'
"value"

answered Apr 15 '22 at 08:23

Logan Lee

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I donwvoted because this [doesn’t](https://unix.stackexchange.com/q/584784/48415) work in some shells due to `<<<`. – bfontaine Jan 02 '23 at 14:22

Can I pass a string variable to jq not the file?

8 Answers8

Valid JSON

`--argjson`

`env`

Nearly-valid JSON

Linked

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