How to extract fields from a json string using jq

Question

How to extract two fields from a JSON file using jq?

When I run 'jq '.node' out.json I get the word 'null' in output

Here is what I have in a file named out.json

head out.json 
{ "items": [ {"node":"aaaa-cn001.me.com","status":"success","result":{"stdout":"3.10.0-957.12.1.el7.x86_64\n","stderr":"","exit_code":0}} , {"node":"aaaa-cn002.me.com","status":"success","result":{"stdout":"3.10.0-957.10.1.el7.x86_64\n","stderr":"","exit_code":0}} , {"node":"aaaa-cn003.me.com","status":"success","result":{"stdout":"3.10.0-957.10.1.el7.x86_64\n","stderr":"","exit_code":0}} , {"node":"aaaa-cn004.me.com","status":"success","result":{"stdout":"3.10.0-957.12.1.el7.x86_64\n","stderr":"","exit_code":0}}

I would like the output to be this way:

aaaa-cn001.me.com 3.10.0-957.12.1.el7.x86_64
aaaa-cn002.me.com 3.10.0-957.10.1.el7.x86_64
aaaa-cn003.me.com 3.10.0-957.10.1.el7.x86_64
aaaa-cn004.me.com 3.10.0-957.12.1.el7.x86_64

Your input isn't JSON. (You're missing ]} at the end). People answering questions are more likely to do so if they don't have to massage your sample data. — William Pursell
– William Pursell, Commented Jun 4, 2019 at 12:52

Aaron · Accepted Answer · 2019-06-04 12:45:00Z

10

Looks like you want the following :

jq --raw-output '.items[] | .node + " " + .result.stdout' out.json

You can try it here

answered Jun 4, 2019 at 12:45

Aaron

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3 Comments

William Pursell Over a year ago

Op probably wants -r as well.

Aaron Over a year ago

@WilliamPursell --raw-output is -r's long form :)

rony thomas Over a year ago

@Aaron Thank you so much!. I can't tell you how happy I am seeing the result your command produced. You nailed it!!

Dmitry · Accepted Answer · 2019-06-04 17:34:10Z

if interested in an alternative solution, there's anoter way of achieving the same - using a walk-path based unix utility jtc:

bash $ <out.json jtc -w'[items][:][node]<n>v[-1][result][stdout]' -T'"{n} {}"' -qq
aaaa-cn001.me.com 3.10.0-957.12.1.el7.x86_64

aaaa-cn002.me.com 3.10.0-957.10.1.el7.x86_64

aaaa-cn003.me.com 3.10.0-957.10.1.el7.x86_64

aaaa-cn004.me.com 3.10.0-957.12.1.el7.x86_64

bash $

Note, an extra line occurs here, because stdout values carry trailing \n, which upon unquoting JSON string (-qq) results in the extra spacer.

If you like to print w/o preserving that line, use this form then:

bash $ <out.json jtc -w'[items][:][node]<n>v[-1][result][stdout]:<(.*)\\n>R' -T'"{n} {$1}"' -qq
aaaa-cn001.me.com 3.10.0-957.12.1.el7.x86_64
aaaa-cn002.me.com 3.10.0-957.10.1.el7.x86_64
aaaa-cn003.me.com 3.10.0-957.10.1.el7.x86_64
aaaa-cn004.me.com 3.10.0-957.12.1.el7.x86_64
bash $

PS> Disclosure: I'm the creator of the jtc - shell cli tool for JSON operations

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