This question already has answers here:
Read JSON data in a shell script [duplicate]
(4 answers)
Closed 7 years ago.
Let's say that we have this kind of JSON file:
{
...
"quotes":{
"SOMETHING":10,
...
"SOMETHING_ELSE":120.4,
...
} }
How can I obtain those values and use them in order to add them together?
Am I able to do even this?
#!/bin/bash
#code ...
echo "$SOMETHING + $SOMETHING_ELSE" | bc
#code ...
#exit
I will obtain the JSON file with wget command. All I want is the content from this file.
Can you help me, please? I am a beginner in shell programming.
I usually use jq, a really fast json parser, to do this kind of things (because parsing a json file with tools like awk or sed is really error-prone).
Given an input file like this:
# file: input.json
{
"quotes":{
"SOMETHING":10,
"SOMETHING_ELSE":120.4
}
}
You can obtain the sum of the 2 fields with a simple filter:
jq '.quotes.SOMETHING + .quotes.SOMETHING_ELSE' input.json
# output -> 130.4
NOTE: jq is available in every major linux distribution. In a debian-derivative system you can install with a sudo apt-get install jq.
This will print out the sum of the selected lines' floats.
#!/bin/bash
awk '{ if ($1 ~ /"SOMETHING":/) {print}; if ($1 ~ /"SOMETHING_ELSE":/) {print} }' $1 | cut -d: -f2 | cut -d, -f1 | awk '{s+=$1};END{print s}'
This finds the lines you want, the plucks out the numbers, and adds them.
You should look up and learn jq as shown in Read the json data in shell script.
The tools in a "normal" shell installation like awk and sed all predate JSON by decades, and are a very very bad fit. jq is worth the time to learn.
Or use Python instead.
Related
This question already has an answer here:
"Argument list too long" while slurping JSON files [duplicate]
(1 answer)
Closed 1 year ago.
There are more than 6k JSON files, each containing exactly one JSON object. I want to prepare one list of objects from these JSONs.
When I am running below jq command I am getting an error.
Kedar.Javalkar#KD2806 MINGW64 /c/zz
$ jq -s '.' inventoryItem_*.json > inventory_items_result_$(date +"%Y%m%d_%H%M%S").json
bash: /usr/bin/jq: Argument list too long
I tried ulimit -s unlimited but the same error
I am using a windows 10 git bash
This is a job that xargs is created to fix -- splitting lists of items into individual command lines that are within the permitted limit.
Because running jq -s a single time is different from concatenating the results of multiple smaller runs, it's appropriate to use xargs to combine cat invocations using the manner described in the linked duplicate.
printf '%s\0' inventoryItem_*.json \
| xargs -0 cat \
| jq -s . \
>"inventory_items_result_$(date +"%Y%m%d_%H%M%S").json"
This question already has answers here:
Argument list too long error for rm, cp, mv commands
(31 answers)
Closed 1 year ago.
I have thousands of JSON files, and I want to merge them into a single one. I'm using the command below to do this.
jq -s . -- *.json > result.json
But I am getting argument list too long error, probably because of the number of files I'm trying to merge. Is there any workaround for this issue?
Built-in commands are immune to that limitation, and printf is one of them. In conjunction with xargs, it would help a lot to achieve this.
printf '%s\0' *.json | xargs -0 cat -- | jq -s .
This question already has answers here:
How to parse json response in the shell script?
(4 answers)
Extract json value with sed
(5 answers)
Closed 2 years ago.
This command
ubus -S call system board
gives me this output
{"kernel":"4.14.195","hostname":"OpenWrt","system":"ARMv7 Processor rev 1 (v7l)","model":"Linksys WRT32X","board_name":"linksys,venom","release":{"distribution":"OpenWrt","version":"19.07.4","revision":"r11208-ce6496d796","target":"mvebu/cortexa9","description":"OpenWrt 19.07.4 r11208-ce6496d796"}}
I want to just extract the model and, if there's a space, replace it with an underscore so I end up with
Linksys_WRT32X
Your command output is json, you can extract the value of the "model" field in pure text and use sed to replace any spaces with underscore.
<command> | jq -r '.model' | sed 's/ /_/g'
or using one jq command to select and replace the text value (thanks #Cyrus)
<command> | jq -r '.model | sub(" "; "_")'
If you don't have jq here is an awk for this
awk -v RS=, -F: '$1 ~ /model/{gsub(/\"/,""); gsub(" ","_"); print $2}'
Have in mind, that one awk or sed for this specific output is fine, but if this was for any json, it could break, json is not text, it can be printed in various lines, it can have additional spaces in places etc.
There are many ways to do this. Here's another one:
ubus -S call system board | sed 's/.*"model":"\([^"]*\)".*$/\1/' | tr ' ' _
I would attempt to answer this using my own version. Since GNU grep has support for Perl regex, we can get the result using:
ubus -S call system board | grep -oP '"model":"\K[^"]+' | tr ' ' _
We attempt to take advantage of the pattern that the JSON key-value pair is of the form "key-name":"<value>" and try to capture the <value> part using grep.
This question already has answers here:
Modify a key-value in a json using jq in-place
(8 answers)
Closed 1 year ago.
I have a daemon.json file which contains one line as below
{ "insecure-registries":["192.X.X.X:8123"] }
I am trying to use a variable to change generically to the current IP address. In bash script normally
I'd store in a variable like
myip=hostname -I | awk '{print $1}'
{ "insecure-registries":["$myip:8123"] }
How to use a kind of variable in JSON file?
If you have access to jq, I would recommend storing not JSON, but a jq filter, like
{"insecure-registries": ["\($ip):8123"]}
Assume the preceding is in file named foo.jq; then using jq as follows to produce JSON from the filter.
$ myip=$(hostname -I | awk '{print $1}') # 192.0.2.42, e.g.
$ jq -nf foo.jq --arg ip "$myip"
{
"insecure-registries": [
"192.0.2.42:8123"
]
}
JSON itself doesn't have a notion of substitution, and bash itself isn't really suitable for making substitutions like this.
I'd like a unix one-liner that will output the current execution environment as a JSON structure like: { "env-var" : "env-value", ... etc ... }
This kinda works:
(echo "{"; printenv | sed 's/\"/\\\"/g' | sed -n 's|\(.*\)=\(.*\)|"\1"="\2"|p' | grep -v '^$' | paste -s -d"," -; echo "}")
but has some extra lines and I think won't work if the environment values or variables have '=' or newlines in them.
Would prefer pure bash/sh, but compact python / perl / ruby / etc one-liners would also be appreciated.
Using jq 1.5 (e.g. jq 1.5rc2 -- see http://stedolan.github.io/jq):
$ jq -n env
This works for me:
python -c 'import json, os;print(json.dumps(dict(os.environ)))'
It's pretty simple; the main complication is that os.environ is a dict-like object, but it is not actually a dict, so you have to convert it to a dict before you feed it to the json serializer.
Adding parentheses around the print statement lets it work in both Python 2 and 3, so it should work for the forseeable future on most *nix systems (especially since Python comes by default on any major distro).
#Alexander Trauzzi asked: "Wondering if anyone knows how to do this, but only passing a subset of the current environment's variables?"
I just found the way to do this:
jq -n 'env | {USER, HOME, PS1}'