Get value of json with bash

Question

I have json file with the following structure

{ "tool_first":"1.1.1","tool_second":"2.2.2","tool_three":"3.3.3" }

And I want to retrieve version from it with bash grep. I create something like this

cat myjson.json | grep -Po '"tool_second":\K"[A-Za-z0-9/._]*"'

which give me output

"2.2.2"

How to use variable instead of string "tool_second"? I want to have something like

cat myjson.json | grep -Po '"$x":\K"[A-Za-z0-9/._]*"'

where $x is the variable; x = "tool_second". I can't retrieve information from it with variable. How to escape variable properly in this way? I need just version number, without "".

Why parse JSON text with grep?, use a parser that knows the underlying format like jq — Inian
– Inian, Commented Apr 19, 2017 at 14:03
But why? Compare grep to the jq version: jq --arg x tool_second '.[$x]' myjson.json. — Thor
– Thor, Commented Apr 25, 2017 at 13:50

Inian · Accepted Answer · 2017-04-19 14:09:14Z

2

grep is NOT the right tool for parsing JSON text. Use a more syntax aware tool like jq. Use the answer below only for trivial purposes.

You are not escaping your double-quotes in your string to search present in variable x,

x="\"tool_second\""
grep -Po "$x:\K\"[A-Za-z0-9/._]*\"" file
"2.2.2"

and it can work for other strings too!

x="\"tool_first\""
grep -Po "$x:\K\"[A-Za-z0-9/._]*\"" file
"1.1.1"

edited Apr 19, 2017 at 14:09

answered Apr 19, 2017 at 14:08

Inian

87k15 gold badges166 silver badges183 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

ndnenkov Over a year ago

Who/what are you quoting here?

Tatarinho Over a year ago

It's not working. In best case it gives me list of all values.

Inian Over a year ago

@Tatarinho: It is working fine for me with your input json in question, can you post your actual file you are testing with?

Collectives™ on Stack Overflow

Get value of json with bash

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related