Check S3 Bucket Existence

Mohammad Abu Mattar
Bash
Published: 11 Jun, 2025
02 Mins read

🚀 Quick Tip

Don’t let your deployment blow up because of a missing S3 bucket. This Bash script lets you check if a bucket exists before anything fails clean and simple.

🔍 The Problem

If your CI/CD pipeline tries to upload files or sync data to an S3 bucket that doesn’t exist, things will break fast. You’ll waste time, pipeline minutes, and possibly miss something obvious. A quick pre-check could prevent all that.

🛠️ The Fix

This script checks if an S3 bucket exists using the AWS CLI. It accepts --bucket or --b flags, gives color-coded logs, and adds a bit of fun to your terminal. Perfect for pre-checks in CI/CD jobs or local scripts.

📌 TL;DR

Use this script to check if an S3 bucket exists before your pipeline tries to use it.
Accepts --bucket or --b to pass the bucket name.
Includes clean logs, color output, and fun formatting for better readability.

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#!/usr/bin/env bash
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# Color definitions
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GREEN='\033[0;32m'
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RED='\033[0;31m'
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YELLOW='\033[1;33m'
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CYAN='\033[0;36m'
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NC='\033[0m' # No Color
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#######################################
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# Prints a fun ASCII banner header.
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# Globals:
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#   CYAN
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#   NC
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# Arguments:
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#   None
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# Outputs:
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#   Writes header text to stdout.
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#######################################
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function print_fun() {
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  echo -e "${CYAN}"
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  echo "╭──────────────────────────────╮"
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  echo "│  ☁️  S3 Bucket Checker Bash  │"
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  echo "╰──────────────────────────────╯"
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  echo -e "${NC}"
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}
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#######################################
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# Prints a log message with timestamp and log level.
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# Globals:
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#   CYAN, GREEN, RED, NC
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# Arguments:
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#   $1 - Log level (INFO, SUCCESS, ERROR)
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#   $2 - Log message
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# Outputs:
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#   Writes formatted log message to stdout.
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#######################################
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function log() {
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  local type="$1"
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  local message="$2"
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  local timestamp
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  timestamp=$(date "+%Y-%m-%d %H:%M:%S")
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  case "$type" in
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    INFO)
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      echo -e "${CYAN}[${timestamp}] [INFO]:${NC} $message"
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      ;;
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    SUCCESS)
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      echo -e "${GREEN}[${timestamp}] [SUCCESS]:${NC} $message"
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      ;;
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    ERROR)
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      echo -e "${RED}[${timestamp}] [ERROR]:${NC} $message"
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      ;;
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    *)
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      echo -e "[${timestamp}] [LOG]: $message"
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      ;;
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  esac
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}
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#######################################
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# Initializes script by parsing CLI arguments.
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# Exits with error if bucket name is not provided.
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# Globals:
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#   BUCKET_NAME, YELLOW, NC
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# Arguments:
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#   --bucket | --b <bucket-name>
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# Outputs:
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#   Sets BUCKET_NAME variable.
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#######################################
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function init() {
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  while [[ "$#" -gt 0 ]]; do
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    case "$1" in
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      --bucket|--b)
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        BUCKET_NAME="$2"
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        shift 2
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        ;;
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      *)
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        log ERROR "Unknown argument: $1"
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        exit 1
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        ;;
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    esac
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  done
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  if [[ -z "$BUCKET_NAME" ]]; then
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    log ERROR "Bucket name not provided. Use --bucket or --b to specify it."
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    echo -e "${YELLOW}Example:${NC} ./check_bucket.sh --bucket my-bucket-name"
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    exit 1
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  fi
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}
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#######################################
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# Checks if the specified S3 bucket exists.
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# Globals:
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#   BUCKET_NAME
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# Outputs:
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#   Success or error message to stdout.
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# Returns:
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#   0 if bucket exists, exits with 1 otherwise.
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#######################################
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function check_bucket_exists() {
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  log INFO "Checking if bucket '$BUCKET_NAME' exists..."
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  if aws s3api head-bucket --bucket "$BUCKET_NAME" 2>/dev/null; then
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    log SUCCESS "Bucket '$BUCKET_NAME' exists and is accessible."
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  else
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    log ERROR "Bucket '$BUCKET_NAME' does not exist or access is denied."
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    exit 1
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  fi
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}
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#######################################
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# Main function that runs the script.
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# Calls init and check_bucket_exists in order.
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# Arguments:
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#   Passes all script arguments to init.
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#######################################
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function main() {
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  print_fun
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  init "$@"
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  check_bucket_exists
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}
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main "$@"

✅ Why This Helps

Adding this check to your CI/CD steps helps avoid silly failures and gives you faster feedback if something’s missing or misconfigured. It’s quick, readable, and reusable and you’ll thank yourself later.

💬 Your Turn

How do you handle S3 checks in your automation? Got a trick or tool you use often? Let’s swap ideas.