sed command issues - regex

Question

Background
Original json (test.json): {"rpc-password": "password"}
Expected changed json: {"rpc-password": "somepassword"}
replace_json_str is a function used to replace password with somepassword using sed.
replace_json_str() {
x=$1
sed -i -e 's/\({ "'"$2"'":\)"[^"]*" }/\1"'"$3"'" }/g' $x
}
Unit test: replace_json_str test.json rpc-password somepassword
Issue
After running the above test, I get a file named test.json-e and the contents of the file is the same as before the test was ran, why?

Answer 1

there is a handy command line json tool called jq
cat input.json
{"rpc-password": "password"}
cat update_json.sh
givenkey=$1
givenvalue=$2
inputfile=input.json
outfile=output.json
cat $inputfile | jq . # show input json
jq --arg key1 "$givenkey" --arg val1 "$givenvalue" '.[$key1] = $val1' "$inputfile" > "$outfile"
cat "$outfile" | jq . # render output json
keep in mind jq can handle multiple such key value updates ... execute it
update_json.sh rpc-password somepassword
{
"rpc-password": "password"
}
{
"rpc-password": "somepassword"
}

Answer 2

Depends on which sed you're using.
The command you ran will work as expected with GNU sed.
But BSD sed does not allow for an empty argument to -i, and if you ran the same command, it will use the next argument, -e, as the backup file.
Also, the positioning of the spaces in your pattern don't match your example JSON.