SRJahirTech

AWS Linux Tutorial -- Part 8: Bash Scripting for AWS

By Suraj Ahir 2025-10-29 11 min read

The AWS CLI is powerful on its own, but combined with bash scripting, it becomes a complete automation platform. You can launch and configure EC2 instances programmatically, automate backups to S3, deploy applications, send alerts on failures, and build entire infrastructure workflows that run on schedule.

AWS CLI Query with --query

# Get only running instances
aws ec2 describe-instances \
  --filters "Name=instance-state-name,Values=running" \
  --query "Reservations[*].Instances[*].[InstanceId,PublicIpAddress,Tags[?Key==Name].Value | [0]]" \
  --output table

# Get instance IDs only
aws ec2 describe-instances \
  --query "Reservations[*].Instances[*].InstanceId" \
  --output text

# Get latest AMI ID for Ubuntu 22.04
aws ec2 describe-images \
  --owners 099720109477 \
  --filters "Name=name,Values=ubuntu/images/hvm-ssd/ubuntu-jammy-22.04-amd64-server-*" \
  --query "sort_by(Images, &CreationDate)[-1].ImageId" \
  --output text

Launch EC2 from Script

#!/bin/bash
set -euo pipefail

AMI_ID="ami-0287a05f0ef0e9d9a"  # Ubuntu 22.04 ap-south-1
INSTANCE_TYPE="t3.micro"
KEY_NAME="my-key"
SECURITY_GROUP="sg-0123456789abcdef"
SUBNET_ID="subnet-0123456789abcdef"

echo "Launching EC2 instance..."
INSTANCE_ID=$(aws ec2 run-instances \
  --image-id $AMI_ID \
  --instance-type $INSTANCE_TYPE \
  --key-name $KEY_NAME \
  --security-group-ids $SECURITY_GROUP \
  --subnet-id $SUBNET_ID \
  --tag-specifications "ResourceType=instance,Tags=[{Key=Name,Value=auto-server}]" \
  --query "Instances[0].InstanceId" \
  --output text)

echo "Instance: $INSTANCE_ID"
echo "Waiting for running state..."
aws ec2 wait instance-running --instance-ids $INSTANCE_ID

PUBLIC_IP=$(aws ec2 describe-instances \
  --instance-ids $INSTANCE_ID \
  --query "Reservations[0].Instances[0].PublicIpAddress" \
  --output text)

echo "Ready! SSH: ssh -i my-key.pem ubuntu@$PUBLIC_IP"

Deploy Application Script

#!/bin/bash
# deploy.sh -- Download and deploy app from S3
set -e

APP_NAME="myapp"
S3_BUCKET="my-deployments"
VERSION=${1:-latest}

log() { echo "[$(date +%H:%M:%S)] $1"; }

log "Deploying $APP_NAME version $VERSION"

# Download from S3
aws s3 cp "s3://${S3_BUCKET}/${APP_NAME}-${VERSION}.tar.gz" /tmp/

# Extract
tar -xzf "/tmp/${APP_NAME}-${VERSION}.tar.gz" -C /opt/

# Install dependencies
cd /opt/$APP_NAME
pip3 install -r requirements.txt

# Restart service
sudo systemctl restart $APP_NAME

# Health check
for i in $(seq 1 5); do
    curl -sf http://localhost:8000/health && { log "Healthy!"; exit 0; }
    log "Attempt $i failed, waiting..."
    sleep 10
done

log "ERROR: Health check failed after deployment"
exit 1

Frequently Asked Questions

In Part 9, we master the AWS CLI with advanced queries, output formats, and profiles.

Written by

Suraj Ahir

Cloud & DevOps engineer running four live production services on my own AWS infrastructure. I write everything on this site myself — no ghostwriters, no AI filler.

More about me → GitHub LinkedIn

Real Automation Scripts Used in Production

#!/bin/bash
# Create EBS snapshots for all production instances
set -euo pipefail

RETENTION_DAYS=7
ENVIRONMENT="production"

log() { echo "[$(date +%Y-%m-%dT%H:%M:%S)] $1"; }

# Get all production instance IDs
INSTANCES=$(aws ec2 describe-instances   --filters "Name=tag:Environment,Values=${ENVIRONMENT}"              "Name=instance-state-name,Values=running"   --query "Reservations[*].Instances[*].InstanceId"   --output text)

for INSTANCE_ID in $INSTANCES; do
    INSTANCE_NAME=$(aws ec2 describe-instances       --instance-ids $INSTANCE_ID       --query "Reservations[0].Instances[0].Tags[?Key=='Name'].Value | [0]"       --output text)
    
    # Get volumes attached to instance
    VOLUMES=$(aws ec2 describe-volumes       --filters "Name=attachment.instance-id,Values=${INSTANCE_ID}"       --query "Volumes[*].VolumeId" --output text)
    
    for VOLUME_ID in $VOLUMES; do
        SNAP_ID=$(aws ec2 create-snapshot           --volume-id $VOLUME_ID           --description "Automated backup of ${INSTANCE_NAME} ${INSTANCE_ID}"           --tag-specifications "ResourceType=snapshot,Tags=[
            {Key=Name,Value=auto-${INSTANCE_NAME}-$(date +%Y%m%d)},
            {Key=CreatedBy,Value=automation},
            {Key=RetentionDays,Value=${RETENTION_DAYS}}
          ]"           --query "SnapshotId" --output text)
        log "Created snapshot ${SNAP_ID} for volume ${VOLUME_ID} (${INSTANCE_NAME})"
    done
done

# Clean up old snapshots older than RETENTION_DAYS
OLD_SNAPS=$(aws ec2 describe-snapshots   --filters "Name=tag:CreatedBy,Values=automation"   --query "Snapshots[?StartTime<='$(date -d "-${RETENTION_DAYS} days" +%Y-%m-%dT%H:%M:%S)'].SnapshotId"   --output text)

for SNAP_ID in $OLD_SNAPS; do
    aws ec2 delete-snapshot --snapshot-id $SNAP_ID
    log "Deleted old snapshot: ${SNAP_ID}"
done

log "Backup automation complete"

Automated Cost Report Script

#!/bin/bash
# Send daily AWS cost summary

YESTERDAY=$(date -d "yesterday" +%Y-%m-%d)
TODAY=$(date +%Y-%m-%d)

COST=$(aws ce get-cost-and-usage   --time-period Start=$YESTERDAY,End=$TODAY   --granularity DAILY   --metrics BlendedCost   --query "ResultsByTime[0].Total.BlendedCost.Amount"   --output text)

COST_ROUNDED=$(printf "%.2f" $COST)

# Send via SES
aws ses send-email   --from "alerts@mycompany.com"   --to "team@mycompany.com"   --subject "AWS Daily Cost: \$${COST_ROUNDED} for $YESTERDAY"   --text "AWS spend for $YESTERDAY: \$${COST_ROUNDED} USD"   --region us-east-1

AWS CLI Pagination and Large Result Sets

#!/bin/bash
# Process ALL EC2 instances across all regions

REGIONS=$(aws ec2 describe-regions --query "Regions[*].RegionName" --output text)

for REGION in $REGIONS; do
    echo "=== Region: $REGION ==="
    
    # --paginate handles multiple pages automatically
    aws ec2 describe-instances         --region $REGION         --query "Reservations[*].Instances[*].[InstanceId,State.Name,InstanceType,Tags[?Key=='Name'].Value|[0]]"         --output text 2>/dev/null
done

Parallel AWS Operations

#!/bin/bash
# Tag 100 instances in parallel (much faster than sequential)

INSTANCES=$(aws ec2 describe-instances   --filters "Name=tag:Environment,Values=untagged"   --query "Reservations[*].Instances[*].InstanceId"   --output text)

# Run 10 tagging operations in parallel using GNU parallel
echo $INSTANCES | tr ' ' '
' | parallel -j10   aws ec2 create-tags --resources {} --tags Key=Project,Value=myapp

# Alternative: xargs with -P for parallel
echo $INSTANCES | tr ' ' '
' | xargs -P10 -I{}   aws ec2 create-tags --resources {} --tags Key=Project,Value=myapp