memory - How to save in XML/JSON format all information from “free” command and “vmstat” command including time?

I need it every 2 minutes:

I am using Debian (text mode only).

Answer

Assuming you don't want individual tags for total, used, free shared etc, you can wrap the whole output in enclosing tags, as appropriate:

XML

The following script could be saved as (eg) memoryinfo-xml.sh:

#!/bin/bash
# memoryinfo-xml.sh - wrap output of free + vmstat in XML tags
echo "
"
  echo -e "\t$(date)"
  echo -e "\t$(free)"
  echo -e "\t$(vmstat)"
echo "
" 

example output:

                                                                                                          
    Thu 30 Mar 16:21:18 BST 2017
                 total       used       free     shared      buffers     cached
Mem:       3853532    3721596     131936     100868     227652    3024584
-/+ buffers/cache:     469360    3384172
Swap:      1182716       2512    1180204
    procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
1  0   2512 132084 227652 3024584    0    0     3     2    4    4  1  0 99  0  0

As you can see, it isn't exactly pretty!

JSON

Very similar to before, save as (eg) memoryinfo-json.sh:

#!/bin/bash
# memoryinfo-json.sh - wrap output of free + vmstat in json
# thanks to https://stackoverflow.com/a/1252191 for \n replacement
echo "{ \"output\":"
  echo -e "\t { \"date\":  \"$(date)\", "
  echo -e "\t  \"free\":   \"$(free | sed ':a;N;$!ba;s/\n/||/g')\", "
  echo -e "\t  \"vmstat\": \"$(vmstat| sed ':a;N;$!ba;s/\n/||/g')\" "
echo "}"

example output:

{
    "output": {
        "date": "Thu 30 Mar 16: 48: 51 BST 2017",
        "free": "total used free shared buffers cached || Mem: 3853532 3722428 131104 100868 227888 3024844 || -/+ buffers/cache: 469696 3383836 || Swap: 1182716 2512 1180204",
        "vmstat": "procs-- -- -- -- -- - memory-- -- -- -- -- -- - swap-- -- -- - io-- -- - system-- -- -- --cpu-- -- - || r b swpd free buff cache si so bi bo in cs us sy id wa st || 1 0 2512 131096 227888 3024844 0 0 3 2 4 4 1 0 99 0 0"
    }
}

Note that to get valid JSON, the newlines have been replaced by a double pipe character (||), via sed replacement.