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I am attempting to gather basic disk space information from a server using a bash script, and store the output in JSON format. I am looking to record the available & used disk space.

An example output of df -h:

Filesystem                      Size  Used Avail Use% Mounted on

udev                            2.0G  4.0K  2.0G   1% /dev

tmpfs                           394M  288K  394M   1% /run

/dev/mapper/nodequery--vg-root   45G  1.4G   41G   4% /

none                            4.0K     0  4.0K   0% /sys/fs/cgroup

none                            5.0M     0  5.0M   0% /run/lock

none                            2.0G     0  2.0G   0% /run/shm

none                            100M     0  100M   0% /run/user

/dev/sda2                       237M   47M  178M  21% /boot

/dev/sda1                       511M  3.4M  508M   1% /boot/efi

As an example this is how I would like the final output to look.

{

  "diskarray": [{

    "mount": "/dev/disk1",

    "spacetotal": "35GB",

    "spaceavail": "1GB"

  },

  {

    "mount": "/dev/disk2",

    "spacetotal": "35GB",

    "spaceavail": "4GB"

  }]

}

So far I've tried using awk:

df -P -B 1 | grep '^/' | awk '{ print $1" "$2" "$3";" }'

with the following output:

/dev/mapper/nodequery--vg-root 47710605312 1439592448;

/dev/sda2 247772160 48645120;

/dev/sda1 535805952 3538944;

But I'm not sure how I take that data and store it in the JSON format.

The following does what you want, with the only requirement external to bash being a Python interpreter:

python_script=$(cat <<'EOF'

import sys, json



data = {'diskarray': }

for line in sys.stdin.readlines():

    mount, avail, total = line.rstrip(';').split()

    data['diskarray'].append(dict(mount=mount, spacetotal=total, spaceavail=avail))

sys.stdout.write(json.dumps(data))

EOF

)



df -Ph | awk '/^// { print $1" "$2" "$3";" }' | python -c "$python_script"

An alternate implementation using jq might look like this:

df -Ph | 

  jq -R -s '

    [

      split("n") |

      . |

      if test("^/") then

        gsub(" +"; " ") | split(" ") | {mount: .[0], spacetotal: .[1], spaceavail: .[2]}

      else

        empty

      end

    ]'

You can do:

$ df -Ph | awk '/^// {print $1"t"$2"t"$4}' | python -c 'import json, fileinput; print json.dumps({"diskarray":[dict(zip(("mount", "spacetotal", "spaceavail"), l.split())) for l in fileinput.input()]}, indent=2)'

{

  "diskarray": [

    {

      "mount": "/dev/disk1", 

      "spacetotal": "931Gi", 

      "spaceavail": "623Gi"

    }, 

    {

      "mount": "/dev/disk2s2", 

      "spacetotal": "1.8Ti", 

      "spaceavail": "360Gi"

    }

  ]

}

Alternative Oneliner

$ df -hP | awk 'BEGIN {printf"{"discarray":["}{if($1=="Filesystem")next;if(a)printf",";printf"{"mount":""$6"","size":""$2"","used":""$3"","avail":""$4"","use%":""$4""}";a++;}END{print"]}";}'



{

   "discarray":[

      {

         "mount":"/",

         "size":"3.9G",

         "used":"2.2G",

         "avail":"1.5G",

         "use%":"1.5G"

      },

      {

         "mount":"/dev",

         "size":"24G",

         "used":"0",

         "avail":"24G",

         "use%":"24G"

      }

   ]

}