I have a following json
{
"kind":"testObject",
"spec":{
},
"status":{
"code":"503"
}
}
I would like to just retrieve the value of code, so that it would just show 503 as an output.
I did try with JMESPath, but that binary is out of question, and not sure what to use.
Access the value with .status.code:
$ jq '.status.code' <<JSON
{
"kind":"testObject",
"spec":{
},
"status":{
"code":"503"
}
}
JSON
"503"
If you want your output to be 503 (as compared to "503"), use --raw-output/-r:
$ jq -r '.status.code' <<JSON
{
"kind":"testObject",
"spec":{
},
"status":{
"code":"503"
}
}
JSON
503
Since this question has the jmespath tag, it is worth pointing out that one could use the JMESPATH command-line tool, jp, as follows:
jp status.code
or to suppress the quotation marks:
jp -u status.code
Similarly, using jaq, which has a jq-based syntax, one could write:
jaq .status.code
or to suppress the quotation marks:
jaq -r .status.code
Related
I have a file with JSON like:
test.json
{
"NUTS|/nuts/2010": {
"type": "small",
"mfg": "TSQQ",
"colors": []
}
}
I am getting "NUTS|/nuts/2010" from outside and I am storing it in a shell variable. I am trying to use the below snippet and using jq util, but I am not able to access the corresponding json against the above key.
test.sh
#!/bin/bash
NUTS_PATH="NUTS|/nuts/2010" #Storing in shell variable
INPUT_FILE="test.json"
RESULT=($(jq -r --arg NUTS_PATH_ALIAS "$NUTS_PATH" '.[$NUTS_PATH_ALIAS]' $INPUT_FILE))
echo "Result: $RESULT"
echo $RESULT > item.json
When I run this, I am getting:
Result: {
But it should return
{
"type": "small",
"mfg": "TSQQ",
"colors": []
}
Any help. Thanks
The problem isn't associated with jq at all. What you have should work fine, but the issue is with the assignment of the result to an array when you might have intended to store it in a variable
RESULT=($(jq -r --arg NUTS_PATH_ALIAS "$NUTS_PATH" '.[$NUTS_PATH_ALIAS]' $INPUT_FILE))
# ^^^ =( .. ) result is stored into an array
A variable like expansion of an array of form $RESULT refers to element at index 0, i.e. ${RESULT[0]}, which contains the { character of the raw JSON output
You should ideally be doing
RESULT="$(jq -r --arg NUTS_PATH_ALIAS "$NUTS_PATH" '.[$NUTS_PATH_ALIAS]' "$INPUT_FILE")"
I always end up swearing at jq, too!
For me, this jq query works:
$ jq '.["NUTS|/nuts/2010"]' test.json
{
"type": "small",
"mfg": "TSQQ",
"colors": []
}
However, because you've got pipes and slashes in your string, the variable quoting gets a bit funny.
NUTS_PATH='"NUTS|/nuts/2010"' #Note the two sets of quotes
INPUT_FILE="test.json"
RESULT=$(jq ".[$NUTS_PATH]" $INPUT_FILE)
echo "Result: $RESULT"
Result: {
"type": "small",
"mfg": "TSQQ",
"colors": []
}
Disclaimer, I'm not a BASH expert, there may (probably is) be a better way to sort out the quoting
Let's say 123.json with below content:
{
"LINE" : {
"A_serial" : "1234",
"B_serial" : "2345",
"C_serial" : "3456",
"X_serial" : "76"
}
}
If I want to use a shell script to change the parameter of X_serial by the original number +1 which is 77 in this example.
I have tried the below script to take out the parameter of X_serial:
grep "X_serial" 123.json | awk {print"$3"}
which outputs 76. But then I don't know how to make it into 77 and then put it back to the parameter of X_serial.
It's not a good idea to use line-oriented tools for parsing/manipulating JSON data. Use jq instead, for example:
$ jq '.LINE.X_serial |= "\(tonumber + 1)"' 123.json
{
"LINE": {
"A_serial": "1234",
"B_serial": "2345",
"C_serial": "3456",
"X_serial": "77"
}
}
This simply updates .LINE.X_serial by converting its value to a number, increasing the result by one, and converting it back to a string.
You need to install powerful JSON querying processor like jq processor. you can can easily install from here
once you install jq processor, try following command to extract the variable from JSON key value
value=($(jq -r '.X_serial' yourJsonFile.json))
you can modify the $value as you preferred operations
With pure Javascript: nodejs and bash :
node <<EOF
var o=$(</tmp/file);
o["LINE"]["X_serial"] = parseInt(o["LINE"]["X_serial"]) + 1;
console.log(o);
EOF
Output
{ LINE:
{ A_serial: '1234',
B_serial: '2345',
C_serial: '3456',
X_serial: 78 }
}
sed or perl, depending on whether you just need string substitution or something more sophisticated, like arithmetic.
Since you tried grep and awk, let's start with sed:
In all lines that contain TEXT, replace foo with bar
sed -n '/TEXT/ s/foo/bar/ p'
So in your case, something like:
sed -n '/X_serial/ s/\"76\"/\"77\"/ p'
or
$ cat 123.json | sed '/X_serial/ s/\"76\"/\"77\"/' > new.json
This performs a literal substiution: "76" -> "77"
If you would like to perform arithmetic, like "+1" or "+10" then use perl not sed:
$ cat 123.json | perl -pe 's/\d+/$&+10/e if /X_serial/'
{
"LINE" : {
"A_serial" : "1234",
"B_serial" : "2345",
"C_serial" : "3456",
"X_serial" : "86"
}
}
This operates on all lines containing X_serial (whether under "LINE" or under something else), as it is not a json parser.
[
{
"name":"sandboxserver.tar.gz.part-aa",
"hash":"010d126f8ccf199f3cd5f468a90d5ae1",
"bytes":4294967296,
"last_modified":"2018-10-10T01:32:00.069000",
"content_type":"binary/octet-stream"
},
{
"name":"sandboxserver.tar.gz.part-ab",
"hash":"49a6f22068228f51488559c096aa06ce",
"bytes":397973601,
"last_modified":"2018-10-10T01:32:22.395000",
"content_type":"binary/octet-stream"
},
{
"name":"sandboxserver.tar.gz.part-ac",
"hash":"2c5e845f46357e203214592332774f4c",
"bytes":5179281858,
"last_modified":"2018-10-11T08:20:11.566000",
"content_type":"binary/octet-stream"
}
]
I am getting above JSON as response while listing the objects in cloud object storage using curl -l -X GET. How can I get the object "name" assigned to an array while looping through all the objects.
for example
array[1]="sandboxserver.tar.gz.part- aa"
array[2]="sandboxserver.tar.gz.part- ab"
array[3]="sandboxserver.tar.gz.part- ac"
You can use jq.
jq is a powerful tool that lets you read, filter, and write JSON in bash.
You might need to install it first.
Try this:
I've pasted your json into a file:
~$ cat n1.json
[
{
"name":"sandboxserver.tar.gz.part-aa",
"hash":"010d126f8ccf199f3cd5f468a90d5ae1",
"bytes":4294967296,
"last_modified":"2018-10-10T01:32:00.069000",
"content_type":"binary/octet-stream"
},
{
"name":"sandboxserver.tar.gz.part-ab",
"hash":"49a6f22068228f51488559c096aa06ce",
"bytes":397973601,
"last_modified":"2018-10-10T01:32:22.395000",
"content_type":"binary/octet-stream"
},
{
"name":"sandboxserver.tar.gz.part-ac",
"hash":"2c5e845f46357e203214592332774f4c",
"bytes":5179281858,
"last_modified":"2018-10-11T08:20:11.566000",
"content_type":"binary/octet-stream"
}
]
And then used jq to find the names:
~$ jq -r '.[].name' n1.json
sandboxserver.tar.gz.part-aa
sandboxserver.tar.gz.part-ab
sandboxserver.tar.gz.part-ac
If you don't want to depend on external utility like jq, use can use python + bash combo do the trick.
response="$(cat data.json)"
declare -a array
array=($(python -c "import json,sys; data=[arr['name'] for arr in json.loads(sys.argv[1])]; print('\n'.join(data));" "$response"))
echo "${array[#]}"
Advice: Writing embedded python code may soon become unreadable so you may want to put the python code in a separate script and run the script.
I'm going to preface by saying that "no, find a different way to do it" is an acceptable answer here.
Is there a reliable way to store a short bit of JSON in a bash variable for use in a AWS CLI command running from the same script?
I'll be running a job from Jenkins that's updating an AWS Route53 record, which requires UPSERTing a JSON file with the change in records. Because it's running from Jenkins, there's no local storage where I can keep this file, and I'd really like to avoid needing to do a git checkout every time this project will run (which will be once an hour).
Ideally, storing the data in a variable ($foo) and calling it as part of the change-resource-record-sets command would be most convenient given the Jenkins setup, but I'm unfamiliar with exactly how to quote/store JSON inside bash - can it be done safely?
The specific JSON in this case is the following;
{"Comment":"Update DNSName.","Changes":[{"Action":"UPSERT","ResourceRecordSet":{"Name":"alex.","Type":"A","AliasTarget":{"HostedZoneId":"######","DNSName":"$bar","EvaluateTargetHealth":false}}}]}
As an added complication the DNSName value - $bar - needs to be expanded.
You could use a here-doc:
foo=$(cat <<EOF
{"Comment":"Update DNSName.","Changes":[{"Action":"UPSERT","ResourceRecordSet":{"Name":"alex.","Type":"A","AliasTarget":{"HostedZoneId":"######","DNSName":"$bar","EvaluateTargetHealth":false}}}]}
EOF
)
By leaving EOF in the first line unquoted, the contents of the here-doc will be subject to parameter expansion, so your $bar expands to whatever you put in there.
If you can have linebreaks in your JSON, you can make it a little more readable:
foo=$(cat <<EOF
{
"Comment": "Update DNSName.",
"Changes": [
{
"Action": "UPSERT",
"ResourceRecordSet": {
"Name": "alex.",
"Type": "A",
"AliasTarget": {
"HostedZoneId": "######",
"DNSName": "$bar",
"EvaluateTargetHealth": false
}
}
}
]
}
EOF
)
or even (first indent on each line must be a tab)
foo=$(cat <<-EOF
{
"Comment": "Update DNSName.",
"Changes": [
{
"Action": "UPSERT",
"ResourceRecordSet": {
"Name": "alex.",
"Type": "A",
"AliasTarget": {
"HostedZoneId": "######",
"DNSName": "$bar",
"EvaluateTargetHealth": false
}
}
}
]
}
EOF
)
and to show how that is stored, including quoting (assuming that bar=baz):
$ declare -p foo
declare -- foo="{
\"Comment\": \"Update DNSName.\",
\"Changes\": [
{
\"Action\": \"UPSERT\",
\"ResourceRecordSet\": {
\"Name\": \"alex.\",
\"Type\": \"A\",
\"AliasTarget\": {
\"HostedZoneId\": \"######\",
\"DNSName\": \"baz\",
\"EvaluateTargetHealth\": false
}
}
}
]
}"
Because this expands some shell metacharacters, you could run into trouble if your JSON contains something like `, so alternatively, you could assign directly, but be careful about quoting around $bar:
foo='{"Comment":"Update DNSName.","Changes":[{"Action":"UPSERT","ResourceRecordSet":{"Name":"alex.","Type":"A","AliasTarget":{"HostedZoneId":"######","DNSName":"'"$bar"'","EvaluateTargetHealth":false}}}]}'
Notice the quoting for $bar: it's
"'"$bar"'"
│││ │││
│││ ││└ literal double quote
│││ │└ opening syntactical single quote
│││ └ closing syntactical double quote
││└ opening syntactical double quote
│└ closing syntactical single quote
└ literal double quote
It can be stored safely; generating it is a different matter, since the contents of $bar may need to be encoded. Let a tool like jq handle creating the JSON.
var=$(jq -n --arg b "$bar" '{
Comment: "Update DNSName.",
Changes: [
{
Action: "UPSERT",
ResourceRecordSet: {
Name: "alex.",
Type: "A",
AliasTarget: {
HostedZoneId: "######",
DNSName: $b,
EvaluateTargetHealth: false
}
}
}
]
}')
I have a JSON structure, escaped inside another JSON structure, escaped inside another JSON structure.
cat shows the file contents just fine:
🍔 cat test.json
{
"payload": "{\"data\":\"{\\\"nested\\\":1}\"}"
}
I want to assign this to a variable in zsh.
But I am finding that my every attempt to return the cat output from a subshell, gives me the wrong number of backslashes.
🍔 X="$(cat test.json)"
🍔 echo "$X"
{
"payload": "{\"data\":\"{\\"nested\\":1}\"}"
}
🍔 echo $(cat test.json)
{ "payload": "{\"data\":\"{\\"nested\\":1}\"}" }
🍔 echo $(<test.json)
{ "payload": "{\"data\":\"{\\"nested\\":1}\"}" }
Where did my backslashes go? Can I get them back?
I am using zsh 5.2 (x86_64-apple-darwin16.0).
The variable is being set to the correct value. You are either using dash, not bash, or your bash shell has the xpg_echo option set. The zsh built-in echo, though, behaves according to the POSIX specification, which replaces certain escaped characters. Try using printf instead:
$ printf '%s\n' "$X"
{
"payload": "{\"data\":\"{\\\"nested\\\":1}\"}"
}