how to get user input as a value in jq in shell script

Question

I have a JSON file from which I am trying to get a value using below

[a223180n@363748ln41dk012 ~]$ cat status.json| jq  '.details.server1.status'
"UP"

In my script, I have the option where the user will enter the server name. So I need the script to pick that value and update the jq command accordingly I am using below and it is failing.

jq is 1.6 version

[a223180n@363748ln41dk012 ~]$ cat status.json| jq --arg server server1'.details.$server.status'
jq: error: syntax error, unexpected '$', expecting FORMAT or QQSTRING_START (Unix shell quoting issues?) at <top-level>, line 1:
.details.$service.status
jq: 1 compile error

[Difference between single and double quotes in Bash](https://stackoverflow.com/questions/6697753/difference-between-single-and-double-quotes-in-bash) — KamilCuk, Oct 29 '19 at 16:35
Is the missing whitespace in here also missing in your real program? — Charles Duffy, Oct 29 '19 at 16:35
Don't use single quotes if you want a variable to be interpolated. — William Pursell, Oct 29 '19 at 16:36
@WilliamPursell, but they *shouldn't* have the variable interpolated by the shell here; it should be expanded by jq. — Charles Duffy, Oct 29 '19 at 16:37
...however, correct syntax to do that would be `echo '{"key": "value"}' | jq --arg k "key" '.[$k]'` -- or `'.details[$k].status'`, with their undisclosed real data. — Charles Duffy, Oct 29 '19 at 16:37

hobbs · Accepted Answer · 2019-10-29T16:48:18.363

2

< status.json jq --arg server server1 '.details[$server].status'

The dot operator is a special version of the [] operator that only works with literal keys. You have a variable for a key here, so you need the [] operator.

edited Oct 29 '19 at 16:48

answered Oct 29 '19 at 16:39

hobbs

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@CharlesDuffy UUOC eliminated, just for you. :) – hobbs Oct 29 '19 at 16:48
jq: error: syntax error, unexpected '[', expecting FORMAT or QQSTRING_START (Unix shell quoting issues?) at , – Ready2work Oct 29 '19 at 17:18
@oguzismail, the original piped from `cat`, and I complained. – Charles Duffy Oct 30 '19 at 12:47
@Charles nice, but jq can read filenames from command line, is there an advantage of redirecting from a file over specifiying it on the command line? – oguz ismail Oct 30 '19 at 12:50
No particular advantage, no. – Charles Duffy Oct 30 '19 at 14:18

how to get user input as a value in jq in shell script

1 Answers1