Tips: jq

Here I’m just collecting some things I seem to need help remembering and do not have a better place.

jq

[
  { name = "foo", size = "large" },
  { name = "bar", size = "medium" },
  { name = "baz", size = "medium" }
]

Filtering

Filtering by the Value of a Field:

$ jq -r '.[] | select(.size=="medium").name'
bar
baz

Filtering by “content” of a Field (i.e. partial match):

$ jq -r '.[] | select(.size | contains("med")).name'
bar
baz

Output

Including multiple fields in the output:

$ jq -r '.[] | "\(.name) \(.size)"'
foo large
bar medium
baz medium

This allows things like the following which, assuming that my AWS NAT Gateway Resources are tagged with ’env_name’, will give me the set of public IPs used (by my VPCs) in each AWS Region I use. (This is a real example from when someone wanted to write NACL Rules to allow traffic from my VPCs)

for R in ap-south-1 ap-southeast-2 ca-central-1 eu-west-1 me-central-1 us-west-2;
do
  aws ec2 describe-nat-gateways --region=$R --filter Name=tag-key,Values=env_name \
    | jq -r '.NatGateways[] | "\(.Tags[]|select(.Key =="env_name").Value) \(.NatGatewayAddresses[].PublicIp)"' \
    | sort;
done

Other

Serial reboot of AWS EC2 Instances in “this” Region which have a key that matches “my-key-name”:

for INST in $(aws ec2 describe-instances | jq -r '.Reservations[].Instances[]|select(.KeyName|contains("my-key-name")).InstanceId');
do
  aws ec2 reboot-instances --instance-ids $INST;
done

Last updated on Mar 14, 2026

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