bash - Parsing Json data columnwise in shell

Question

When I run a command I get a response like this

{

    "status": "available",
    "managed": true,
    "name":vdisk7,
    "support":{
    "status": "supported"
    },
    "storage_pool": "pfm9253_pfm9254_new",
    "id": "ff10abad"-2bf-4ef3-9038-9ae7f18ea77c",
    "size":100
},

and hundreds of this type of lists or dictionaries I want a command that does such sort of a thing

if name = "something", 
    get the id

Any links that would help me in learning such sort of commands would be highly appreciated

I have tried

awk '{if ($2 == "something") print $0;}'

But I think the response is in Json so the colum wise awk formatting is not working.

Also it's just a single command that I need to run so I would prefer not to use any external library.

Answer 1

JSON parser is better for this task

awk and sed are utilities to parse line-oriented text, but not json. What if your json formatting will change ? (some lines will go on one line ?).

You should use any standard json parser out there. Or use some powerful scripting language, such as PHP, Python, Ruby, etc.

I can provide you with example on how to do it with python.

What if I can't use powerful scripting language ?

If you totally unable to use python, then there is utility jq out there: link

If you have some recent distro, jq maybe already in repositories (example: Ubuntu 13.10 has it in repos).

I can use python!

I would do that using simple python inline script.

For example we have some some_command that returns json as a result.

We have to get value of data["name"].

Here we go:

some_command | python -c "import json, sys; print json.load(sys.stdin)['name']"

It will output vdisk7 in your case

For this to work you need to be sure, json is fully valid.

If you have a list of json objects:

[
  {
    ...
    "name": "vdisk17"
    ...
  },
  {
    ...
    "name": "vdisk18"
    ...
  },
  {
    ...
    "name": "vdisk19"
    ...
  },
...
]

You could use some list comprehensions:

some_command | python -c "import json, sys; [sys.stdout.write(x['name'] + '
') for x in json.load(sys.stdin)]"

It will output:

vdisk17
vdisk18
vdisk19