how to get a value from a json key value pair in linux shell scripting

Question

hi i am writings a small shell script. there i use curl command to call to api. what it return is a status of a scan.

{"status":"14"}

i want to get this status and check if it is less than 100; this is what i have done so far

    a=0

    while [ $a -lt 100 ]
    do

        curlout=$(curl "http://localhost:9090/JSON/spider/view/status/?zapapiformat=JSON&scanId=0");
        echo "$curlout";
       a=`expr $a + 1`
    done

what i want to do is assign that status to $a; how to get read this json to get the value in shell script

sed -r '/status/s/^.*"([0-9]+).*$/\1/' <<< "$curlout" worked for you? — CWLiu
– CWLiu, Commented Sep 28, 2017 at 7:13
post the output of curl "http://localhost:9090/JSON/spider/view/status/?zapapiformat=JSON&scanId=0". And what is the purpose of incrementing the value of status if it's always static? — RomanPerekhrest
– RomanPerekhrest, Commented Sep 28, 2017 at 7:20

chepner · Accepted Answer · 2017-09-28 17:22:59Z

5

If you need to work with JSON, you should obtain jq:

$ echo '{"status": "14"}' | jq '.status|tonumber'
14

or, less rigorously:

$ echo '{"status": "14"}' | jq -r '.status'
14

answered Sep 28, 2017 at 17:22

chepner

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1 Comment

Leonardo Rick Over a year ago

How to set it to a variable

Thirupathi Thangavel · Accepted Answer · 2017-09-28 07:26:22Z

0

If you're sure about the format of the curl output, then it's very simple.

echo "$curlout" | tr -cd '[:digit:]'

From manpage of tr,

   -c, -C, --complement
          use the complement of SET1

   -d, --delete
          delete characters in SET1, do not translate

   [:digit:]
          all digits

So this command removes all characters other than digits.

answered Sep 28, 2017 at 7:26

Thirupathi Thangavel

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