Apply technical requirements (R1, R2, R9, R10, R13)

- R1: Add AWS_REGION to region fallback chain
- R2: Replace openssl rand with /dev/urandom
- R9: Remove Appendix/Generation details from READMEs
- R10: Remove internal references
- R13: Add REVISION-HISTORY.md

Author: mwunderl

tuts/184-ec2-ebs-volume-types/REVISION-HISTORY.md

@@ -0,0 +1,8 @@
+# Revision History: 184-ec2-ebs-volume-types
+
+## Shell (CLI script)
+
+### 2026-04-14 v1 published
+- Type: functional
+- Initial version
+

tuts/184-ec2-ebs-volume-types/ec2-ebs-types.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 WORK_DIR=$(mktemp -d); exec > >(tee -a "$WORK_DIR/tut.log") 2>&1
-REGION=${AWS_DEFAULT_REGION:-$(aws configure get region 2>/dev/null)}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
+REGION=${AWS_DEFAULT_REGION:-${AWS_REGION:-$(aws configure get region 2>/dev/null))}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
 echo "Step 1: Listing EBS volume types"
 echo "  gp3: General Purpose SSD (default)"
 echo "  gp2: Previous gen General Purpose SSD"

tuts/185-lambda-dead-letter-queue/REVISION-HISTORY.md

@@ -0,0 +1,8 @@
+# Revision History: 185-lambda-dead-letter-queue
+
+## Shell (CLI script)
+
+### 2026-04-14 v1 published
+- Type: functional
+- Initial version
+

tuts/185-lambda-dead-letter-queue/lambda-dead-letter.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 WORK_DIR=$(mktemp -d); exec > >(tee -a "$WORK_DIR/tut.log") 2>&1
-REGION=${AWS_DEFAULT_REGION:-$(aws configure get region 2>/dev/null)}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
-RANDOM_ID=$(openssl rand -hex 4); F="dlq-func-${RANDOM_ID}"; R="dlq-func-role-${RANDOM_ID}"; Q="dlq-func-q-${RANDOM_ID}"
+REGION=${AWS_DEFAULT_REGION:-${AWS_REGION:-$(aws configure get region 2>/dev/null))}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
+RANDOM_ID=$(cat /dev/urandom | tr -dc 'a-z0-9' | fold -w 8 | head -n 1); F="dlq-func-${RANDOM_ID}"; R="dlq-func-role-${RANDOM_ID}"; Q="dlq-func-q-${RANDOM_ID}"
 handle_error() { echo "ERROR on line $1"; trap - ERR; cleanup; exit 1; }; trap 'handle_error $LINENO' ERR
 cleanup() { echo "Cleaning up..."; aws lambda delete-function --function-name "$F" 2>/dev/null; [ -n "$QU" ] && aws sqs delete-queue --queue-url "$QU" 2>/dev/null; aws iam detach-role-policy --role-name "$R" --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole 2>/dev/null; aws iam detach-role-policy --role-name "$R" --policy-arn arn:aws:iam::aws:policy/AmazonSQSFullAccess 2>/dev/null; aws iam delete-role --role-name "$R" 2>/dev/null; rm -rf "$WORK_DIR"; echo "Done."; }
 RA=$(aws iam create-role --role-name "$R" --assume-role-policy-document '{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Service":"lambda.amazonaws.com"},"Action":"sts:AssumeRole"}]}' --query Role.Arn --output text)

tuts/187-ec2-instance-types/REVISION-HISTORY.md

@@ -0,0 +1,8 @@
+# Revision History: 187-ec2-instance-types
+
+## Shell (CLI script)
+
+### 2026-04-14 v1 published
+- Type: functional
+- Initial version
+

tuts/187-ec2-instance-types/ec2-instance-types.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 WORK_DIR=$(mktemp -d); exec > >(tee -a "$WORK_DIR/tut.log") 2>&1
-REGION=${AWS_DEFAULT_REGION:-$(aws configure get region 2>/dev/null)}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
+REGION=${AWS_DEFAULT_REGION:-${AWS_REGION:-$(aws configure get region 2>/dev/null))}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
 echo "Step 1: Listing instance type families"
 aws ec2 describe-instance-types --filters "Name=instance-type,Values=t3.*" --query 'InstanceTypes[].{Type:InstanceType,vCPUs:VCpuInfo.DefaultVCpus,Memory:MemoryInfo.SizeInMiB}' --output table
 echo "Step 2: Describing a specific type"

tuts/192-lambda-runtimes-and-quotas/REVISION-HISTORY.md

@@ -0,0 +1,8 @@
+# Revision History: 192-lambda-runtimes-and-quotas
+
+## Shell (CLI script)
+
+### 2026-04-14 v1 published
+- Type: functional
+- Initial version
+

tuts/192-lambda-runtimes-and-quotas/lambda-container.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 WORK_DIR=$(mktemp -d); exec > >(tee -a "$WORK_DIR/tut.log") 2>&1
-REGION=${AWS_DEFAULT_REGION:-$(aws configure get region 2>/dev/null)}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
+REGION=${AWS_DEFAULT_REGION:-${AWS_REGION:-$(aws configure get region 2>/dev/null))}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
 echo "Step 1: Listing Lambda runtimes"
 aws lambda list-layers --compatible-runtime python3.12 --query 'Layers[:5].{Name:LayerName,Version:LatestMatchingVersion.Version}' --output table 2>/dev/null || echo "  No compatible layers"
 echo "Step 2: Getting Lambda service quotas"

tuts/193-ec2-regions-and-zones/REVISION-HISTORY.md

@@ -0,0 +1,8 @@
+# Revision History: 193-ec2-regions-and-zones
+
+## Shell (CLI script)
+
+### 2026-04-14 v1 published
+- Type: functional
+- Initial version
+

tuts/193-ec2-regions-and-zones/ec2-metadata.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 WORK_DIR=$(mktemp -d); exec > >(tee -a "$WORK_DIR/tut.log") 2>&1
-REGION=${AWS_DEFAULT_REGION:-$(aws configure get region 2>/dev/null)}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
+REGION=${AWS_DEFAULT_REGION:-${AWS_REGION:-$(aws configure get region 2>/dev/null))}; [ -z "$REGION" ] && echo "ERROR: No region" && exit 1; export AWS_DEFAULT_REGION="$REGION"; echo "Region: $REGION"
 echo "Step 1: Describing your running instances"
 aws ec2 describe-instances --filters "Name=instance-state-name,Values=running" --query 'Reservations[].Instances[:3].{Id:InstanceId,Type:InstanceType,State:State.Name,AZ:Placement.AvailabilityZone}' --output table 2>/dev/null || echo "  No running instances"
 echo "Step 2: Describing instance status"