Example to start an ECS Fargate task an existing cluster, task definition, and VPC, and then use ECS Exec to open an interactive shell with a containr in the task

aws-cli-ecs-exec-with-fargate.sh

CLUSTER="your_cluster_name"
REGION="cluster_region"
PRIVATE_SUBNETS="subnet-someSubnet123,subnet-someOtherSubnet456"
TASK_SECURITY_GROUP="security-group-for-ECS-task-ID"
PUBLIC_IP_SETTING="DISABLED"
TASK_CONTAINER_NAME_FOR_ECS_EXEC="container-name-for-ecs-exec"

# Run a Fargate task with ECS Exec enabled:
RUN_TASK_RESULT=$(
    aws ecs run-task \
    --task-definition d3be26d92154c50f_ecs_td:13 \
    --enable-execute-command \
    --cluster example \
    --launch-type FARGATE \
    --network-configuration "awsvpcConfiguration={subnets=[$PRIVATE_SUBNETS],securityGroups=[$TASK_SECURITY_GROUP],assignPublicIp=$PUBLIC_IP_SETTING}" \
    --region $REGION \
    --output json
)
TASK_ID=$(echo $RUN_TASK_RESULT | jq -r '.tasks[0].taskArn')

# Use ECS Exec to open a remote shell with your task; you will need to wait for the task to reach a running status, first.
# You may need to change the command to use a different shell, depending on what is installed in your base image. For example, "/bin/bash"
aws ecs execute-command  \
    --region $REGION \
    --cluster $CLUSTER \
    --task $TASK_ID \
    --container $TASK_CONTAINER_NAME_FOR_ECS_EXEC \
    --command '/bin/sh' \
    --interactive

# Stop the task
aws ecs stop-task --cluster $CLUSTER --task $TASK_ID --region $REGION