Cutting string into different types of variables - bash

Question

Full script:
snapshot_details=`az snapshot show -n $snapshot_name -g $resource_group --query \[diskSizeGb,location,tags\] -o json`
echo $snapshot_details
IFS='",][' read -r -a array <<< $snapshot_details
echo ${array[#]}
IFS=' ' read -r -a array1 <<< ${array[#]}
echo ${array1[0]} #size
echo ${array1[1]} #location
How can I break this into 3 different variables:
a=5
b=eastus2
c={ "name": "20190912123307" "namespace": "aj-ssd" "pvc": "poc-ssd" }
and is there any easier way to parse c so that I can easy traverse over all the keys and values?
o/p of the above script is:
[ 5, "eastus2", { "name": "20190912123307", "namespace": "ajain-ssd", "pvc": "azure-poc-ssd" } ]
5 eastus2 { name : 20190912123307 namespace : ajain-ssd pvc : azure-poc-ssd }
5
eastus2

Answer 1

A JSON parser, such as jq, should always be used when splitting out items from a JSON array in bash. Line-oriented tools (such as awk) are unable to correctly escape JSON -- if you had a value with a tab, newline, or literal quote, it would be emitted incorrectly.
Consider the following code, runnable exactly as-is even by people not having your az command:
snapshot_details_json='[ 5, "eastus2", { "name": "20190912123307", "namespace": "ajain-ssd", "pvc": "azure-poc-ssd" } ]'
{ read -r diskSizeGb && read -r location && read -r tags; } < <(jq -cr '.[]' <<<"$snapshot_details_json")
# show that we really got the content
echo "diskSizeGb=$diskSizeGb"
echo "location=$location"
echo "tags=$tags"
...which emits as output:
diskSizeGb=5
location=eastus2
tags={"name":"20190912123307","namespace":"ajain-ssd","pvc":"azure-poc-ssd"}

Answer 2

Bash can do this with the awk command:
To extract the 5 :
awk -F " " '{ print $1 }'
To extract eastus2 :
awk -F "\"" '{ print $2 }'
To extract the last string :
awk -F "{" '{ print "{" $2 }'
As seen here :
To explain quickly
awk -F " " '{ print $1 }'
-F sets a delimiter, here we set space as the delimiter.
Then, we ask awk to print the first occurence before the first delimiter is hit.
The slightly more complex one:
awk -F "{" '{ print "{" $2 }'
Here we set { as the delimiter. Since we wouldn't have the bracket with only printing $2, we're also manually re-printing the bracket (print "{" $2)

Answer 3

It will not be nice in Bash, but this should work if your input format does not vary (including no {, } or spaces inside the key/value pairs):
S='5 "eastus2" { "name": "20190912123307" "namespace": "aj-ssd" "pvc": "poc-ssd" }'
a=`echo "$S" | awk '{print $1}'`
b=`echo "$S" | awk '{print $2}' | sed -e 's/\"//g'`
c=`echo "$S" | awk '{$1=$2=""; print $0}'`
echo "$a"
echo "$b"
echo "$c"
elems=`echo "$c" | sed -e 's/{//' | sed -e 's/}//' | sed -e 's/: //g'`
echo $elems
for e in $elems
do
kv=`echo "$e" | sed -e 's/\"\"/ /' | sed -e 's/\"//g'`
key=`echo "$kv" | awk '{print $1}'`
value=`echo "$kv" | awk '{print $2}'`
echo "key:$key; value:$value"
done
The idea in the iteration over key/value pairs is to:
(1) remove the space (and colon) between keys and corresponding value so that each key/value pair appears as one item.
(2) inside the loop, change the delimiter between keys and values (which is now "") to space and remove the double quotes (variable 'kv').
(3) extract the key/value as the first/second item of kv.
EDIT:
Avoid file name wildcard expansions.