The Amazon Web Services Command Line Interface (AWS CLI) is a powerful tool that allows developers and system administrators to interact with AWS services directly from the terminal. Whether you’re managing EC2 instances, deploying applications, or automating infrastructure tasks, mastering AWS CLI commands is essential for efficient cloud operations.
In this comprehensive guide, we’ll explore the most searched AWS CLI commands and dive deep into the most critical command that every AWS user should master.
Why AWS CLI Matters
Before diving into commands, let’s understand why AWS CLI is indispensable. While the AWS Management Console provides a user-friendly interface, the CLI offers speed, automation capabilities, and scriptability that the console simply cannot match. It’s the bridge between manual operations and full infrastructure-as-code implementations.
The Top 10 Most Searched AWS CLI Commands
Here are the commands that AWS users search for and use most frequently:
1. S3 Operations
# List all S3 buckets
aws s3 ls
# Copy files to S3
aws s3 cp myfile.txt s3://my-bucket/
# Sync directory with S3
aws s3 sync ./local-folder s3://my-bucket/backup/2. EC2 Instance Management
# List EC2 instances
aws ec2 describe-instances
# Start instances
aws ec2 start-instances --instance-ids i-1234567890abcdef0
# Stop instances
aws ec2 stop-instances --instance-ids i-1234567890abcdef03. IAM User Management
# List IAM users
aws iam list-users
# Create new user
aws iam create-user --user-name john-doe4. Lambda Functions
# List Lambda functions
aws lambda list-functions
# Invoke a function
aws lambda invoke --function-name myFunction response.json5. Identity Verification
# Verify your AWS credentials
aws sts get-caller-identityThe Most Important Command: aws ec2 describe-instances
If there’s one AWS CLI command you should master, it’s aws ec2 describe-instances. This command is the cornerstone of EC2 management and provides comprehensive information about your virtual machines in the cloud.
Why This Command is Critical
EC2 (Elastic Compute Cloud) forms the foundation of most AWS infrastructures. Whether you’re troubleshooting connectivity issues, auditing your infrastructure, or building automation scripts, this command is your starting point. It provides real-time information about instance states, IP addresses, security groups, and custom tags.
Basic Usage
# Get all instances
aws ec2 describe-instances-This returns a JSON output with complete details about every EC2 instance in your account for the default region.
Advanced Filtering and Formatting
The real power comes when you combine filters and queries:
# List only running instances with formatted output
aws ec2 describe-instances \
--filters "Name=instance-state-name,Values=running" \
--query 'Reservations[*].Instances[*].[InstanceId,InstanceType,PublicIpAddress,Tags[?Key==`Name`].Value|[0]]' \
--output tablePractical Examples
Example 1: Find Production Instances
aws ec2 describe-instances \
--filters "Name=tag:Environment,Values=production" \
--query 'Reservations[*].Instances[*].[InstanceId,State.Name,PrivateIpAddress]' \
--output textExample 2: Get Instances by Name Pattern
aws ec2 describe-instances \
--filters "Name=tag:Name,Values=WebServer*" \
--query 'Reservations[*].Instances[*].{ID:InstanceId,Name:Tags[?Key==`Name`].Value|[0],IP:PublicIpAddress}' \
--output tableUnderstanding the Query Syntax
The --query parameter uses JMESPath, a query language for JSON. Here’s a breakdown:
Reservations[*]– Iterate through all reservationsInstances[*]– Iterate through all instances[InstanceId,InstanceType]– Select specific fieldsTags[?Key=='Name'].Value|[0]– Filter tags and get the Name tag value
Best Practices
- Always specify regions to avoid confusion
- Use filters to reduce output and improve performance
- Format output appropriately for your use case (table for humans, JSON for scripts)
- Store credentials securely using IAM roles or AWS credentials file
- Use named profiles when managing multiple AWS accounts
Conclusion
Mastering AWS CLI commands, especially aws ec2 describe-instances, significantly improves your productivity and enables powerful automation. Start with these essential commands, practice filtering and querying, and gradually build more complex scripts. The command line might seem intimidating at first, but it quickly becomes your most efficient tool for AWS management.
Frequently Asked Questions (FAQs)
Q1: How do I install AWS CLI?
A: Download from AWS’s official website or use package managers:
# macOS
brew install awscli
# Linux
pip install awscli
# Windows
Download the MSI installer from AWSQ2: How do I configure AWS CLI with my credentials?
A: Run the configuration command:
aws configureThen enter your Access Key ID, Secret Access Key, default region, and output format.
Q3: Can I use AWS CLI with multiple AWS accounts?
A: Yes! Use named profiles:
aws configure --profile production
aws ec2 describe-instances --profile productionQ4: What’s the difference between –output table, json, and text?
A:
- table: Human-readable formatted table
- json: Structured JSON (best for scripts)
- text: Tab-delimited text (good for Unix tools like grep, awk)
Q5: How do I find instances across all regions?
A: Loop through all regions:
for region in $(aws ec2 describe-regions --query 'Regions[*].RegionName' --output text); do
echo "Checking $region"
aws ec2 describe-instances --region $region
done