I have a JSON file that has this content:
{
"Message": {
"greeting": "hello"
}
}
{
"Message": {
"greeting": "Bonjour"
}
}
{
"Message": {
"greeting": "Konnichiwa"
}
}
I would like to extract only the first Message that has "greeting" : "hello".
I can't seem to use an index on it using
cat "$file" | jq -c "."
The above command all returns the three messages. I would like to ask on how to only extract the first message or one by one.
You input file contains several JSON objects. Use -s to read them all into a single array, otherwise jq processes them one by one. Then, you can just print the first one by specifying its index:
jq -cs '.[0]'
jq -cs first
Assuming that you want the first JSON object which has a greeting key corresponding to the value hello, specifically, not just the first JSON object.
jq -s 'map(select(.Message.greeting == "hello")) | first' file.json
This reads the JSON objects in file.json into an array with -s (--surp). This array is then filtered for any object that contains a .Message.greeting key with value hello. The first of these objects is returned.
With a modified example document,
{
"Message": {
"greeting": "Konnichiwa"
}
}
{
"Message": {
"greeting": "hello",
"id": 1
}
}
{
"Message": {
"greeting": "hello",
"id": 2
}
}
{
"Message": {
"greeting": "Bonjour"
}
}
where the id keys were added just to tell two otherwise identical objects apart,
the jq command returns
{
"Message": {
"greeting": "hello",
"id": 1
}
}
sed '/^}/q' < thatfilewhich would save having to read it fully or parse the json in there.