Bash store json response in another variable

Question

I'm curling an endpoint:

#!/bin/bash
instance_info=$(curl -sk https://internal.admin.com/app/instance)

which gives a json response:

{
"basePath": "/install", 
"metadata": {
    "deployed_artifact": "app01", 
    "docker": "True",  
    "http_port": "7471",
    "url": "www.google.com"
}, 
"name": "app-01", 
"server": "webserver1"
}

I'm trying to avoid curling more than once to get the variables I need from the json using JQ.

Using bash I'd really appreciate if someone can show me how to store the response as another var and then use this to variablize name: server: url: http_port:

The following seems to run the curl twice:

#!/bin/bash
instance_info=$(curl -sk https://internal.admin.com/app/instance)

server_name=$(echo instance_info | /usr/bin/jq --raw-output '.server')
url=$(echo instance_info | /usr/bin/jq --raw-output '.url')

I don't see why the curl line would be executed twice. How do you tell it is executed twice? — Cyrille Pontvieux
– Cyrille Pontvieux, Commented Apr 27, 2016 at 10:59
And you can get rid of the echo using /usr/bin/jq <args> <<< "$instance_info". — Michael Jaros
– Michael Jaros, Commented Apr 27, 2016 at 11:05

fedorqui · Accepted Answer · 2016-04-27 11:05:09Z

You are calling curl once and this suffices. Then you have the content in a variable, so you can access it without calling curl again.

Regarding your code, your approach is fine but you are missing $ when you are echoing the variable:

server_name=$(echo $instance_info | /usr/bin/jq --raw-output '.server')
#                  ^

See a sample. Here I hardcode the JSON:

your_json='
{
"basePath": "/install", 
"metadata": {
    "deployed_artifact": "app01", 
    "docker": "True",  
    "http_port": "7471",
    "url": "www.google.com"
}, 
"name": "app-01", 
"server": "webserver1"
}'

for the server:

$ echo "$your_json" | jq --raw-output '.server'
webserver1

For the url you need to indicate the block where it lies on. That is, metadata:

$ echo "$your_json" | jq --raw-output '.metadata.url'
www.google.com

To store into a variable, say:

your_field=$(echo "$your_json" | jq --raw-output 'XXXX')
#                                                 ^^^^

jq170727 · Accepted Answer · 2017-08-26 17:13:09Z

Here is a script which demonstrates how to use jq's @sh formatting directive along with bash eval to set bash variables using the output of a filter. In this case we hardcode the json which presumably would have come from curl.

#!/bin/bash
instance_info='
{
"basePath": "/install", 
"metadata": {
    "deployed_artifact": "app01", 
    "docker": "True",  
    "http_port": "7471",
    "url": "www.google.com"
}, 
"name": "app-01", 
"server": "webserver1"
}'

eval "$(jq -M -r '@sh "server_name=\(.server) url=\(.metadata.url)"' <<< "$instance_info")"

echo $server_name
echo $url

When run this produces the output

webserver1
www.google.com

The Extract data and set shell variables section of the JQ Cookbook has more examples of @sh.

jijinp · Accepted Answer · 2016-04-27 11:13:03Z

1

sed -rn 's/[ ]*"([^"]*)"[^"]*("[^"]*").*/\1=\2/gp'' file.json

O/P:

basePath="/install"
deployed_artifact="app01"
docker="True"
http_port="7471"
url="www.google.com"
name="app-01"
server="webserver1"

eval this output you can get the variable

eval $(sed -rn 's/[ ]*"([^"]*)"[^"]*("[^"]*").*/\1=\2/gp' file.json )
echo $name $server

O/p:

app-01 webserver1

answered Apr 27, 2016 at 11:13

jijinp

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Comments

Cole Tierney · Accepted Answer · 2016-04-27 21:40:26Z

0

Read the values with one jq pass then there's no need to store the json:

read name server url http_port < <(
    curl -sk https://internal.admin.com/app/instance | \
    jq --raw-output '[.name, .server, .metadata.url, .metadata.http_port] | join(" ")'
)

echo -e "\$name: $name\n\$server: $server\n\$url: $url\n\$http_port $http_port"
$name: app-01
$server: webserver1
$url: www.google.com
$http_port 7471

edited Apr 27, 2016 at 21:40

answered Apr 27, 2016 at 12:58

Cole Tierney

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