Shell Script – Change Value In Json File Automatically

Here are some folders which contain json files.
These json files have a version value, just look like the following image.

We will increase this number by 10 for every json file in current folders recursively.
Install command line tool jq to modify json file easily.
Ubuntu: sudo apt-get install jq
Windows: just download exe on the page: https://github.com/jqlang/jq/releases

Jq Read

Command jq '.["foo"]'
Input   {"foo": 42}
Output  42

Command jq '.foo'
Input   {"foo": 42, "bar": "less interesting data"}
Output  42

Jq Remove Key

Command jq 'del(.foo)'
Input   {"foo": 42, "bar": 9001, "baz": 42}
Output  {"bar": 9001, "baz": 42}

Jq assignment

Command	jq '.a = .b'
Input	{"a": {"b": 10}, "b": 20}
Output	{"a":20,"b":20}

Jq add key-value pair

cat fruits.json | jq '.fruit += {"source" : "India" }'
{
  "fruit": {
    "name": "apple",
    "color": "green",
    "price": 1.2,
    "source": "India"
  }
}

Reference page: https://jqlang.github.io/jq/manual/

I test my script on win10 in git-bash environment, you can replace jq-win64 with jq if you are on linux.

run.sh:

set -e
#folder=$1
folder="./"
files=()
echo "start to find json under folder: "$folder
find $folder -name  "*.version.json" -print0 >tmpfile
while IFS=  read -r -d $'\0'; do
    files+=("$REPLY")
done < tmpfile

len=${#files[*]}
echo ${files[@]} #print all
echo "----- length is "${len}
echo ${files[1]}

#exit 0
# install jp on ubuntu firstly
for (( i=0; i<${len}; i++ ))
do
    echo "input file: " ${files[$i]}
    oldValue=`./jq-win64 -r '.["version"]' "${files[$i]}"`
    echo $oldValue;
    newValue=`expr $oldValue + 10`
    echo $oldValue" "$newValue
    ./jq-win64 -r '.version = "'${newValue}'"' "${files[$i]}" > "${files[$i]}.new"
    echo "${files[$i]}.new""===>""${files[$i]}"
    mv "${files[$i]}.new" "${files[$i]}"
done