fix date to work on GNU based linux systems per #1023

Author: jeremybumsted

utils/log-collector

@@ -69,10 +69,18 @@ done
 
 # CloudWatch stores the creationTime as milliseconds since epoch UTC. 
 # Since macOS doesn't support calculating the time since epoch in milliseconds, we don't have perfect accuracy on this, but it should be as close to 24 hours as possible
-# while still being inclusive to all platforms that might run the script
+# We'll check to see if we're running on a macOS-based OS and adjust appropriately, otherwise use the standard date command
 
 # Currently only collects the last 24h of logs, but it might be good to be able to specify a different value for this.
-logAge=$(date -v-1d "+%s000")
+
+logAge=$(date --date="1day" "+%s000")
+
+# check if we're running on a macOS based system
+if [[ $OSTYPE == 'darwin'* ]]; then
+    logAge=$(date -v-1d "+%s000")
+fi
+
+
 
 # Collect some information about the Lambda function and associated log groups
 lambdaFunction=$(aws cloudformation describe-stack-resources --stack-name "$stackName" --logical-resource-id Autoscaling --query "StackResources[*].PhysicalResourceId" --output text | sed -nr 's/.*stack\/(.*)\/.*/\1/p')