Create and manage a sorted directory structure in AWS S3

Upload many files to S3 with automatic organization by first-character prefixes.

S3 Bulk Upload

Upload files to S3 with automatic organization using first-character prefixes (e.g., a/apple.txt, b/banana.txt, 0-9/123.txt).

Quick Start

Use the included script for bulk uploads:

bash

# Basic upload
./s3-bulk-upload.sh ./files my-bucket

# Dry run to preview
./s3-bulk-upload.sh ./files my-bucket --dry-run

# Use sync mode (faster for many files)
./s3-bulk-upload.sh ./files my-bucket --sync

# With storage class
./s3-bulk-upload.sh ./files my-bucket --storage-class STANDARD_IA

Prerequisites

Verify AWS credentials are configured:

bash

aws sts get-caller-identity

If this fails, ensure AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY are set, or configure via aws configure.

Organization Logic

Files are organized by the first character of their filename:

First Character	Prefix
a-z	Lowercase letter (e.g., a/, b/)
A-Z	Lowercase letter (e.g., a/, b/)
0-9	0-9/
Other	_other/

Single File Upload

Upload a single file with automatic prefix:

bash

FILE="example.txt"
BUCKET="my-bucket"

# Compute prefix from first character
FIRST_CHAR=$(echo "${FILE}" | cut -c1 | tr '[:upper:]' '[:lower:]')
if [[ "$FIRST_CHAR" =~ [a-z] ]]; then
  PREFIX="$FIRST_CHAR"
elif [[ "$FIRST_CHAR" =~ [0-9] ]]; then
  PREFIX="0-9"
else
  PREFIX="_other"
fi

aws s3 cp "$FILE" "s3://${BUCKET}/${PREFIX}/${FILE}"

Bulk Upload

Upload all files from a directory:

bash

SOURCE_DIR="./files"
BUCKET="my-bucket"

for FILE in "$SOURCE_DIR"/*; do
  [ -f "$FILE" ] || continue
  BASENAME=$(basename "$FILE")
  FIRST_CHAR=$(echo "$BASENAME" | cut -c1 | tr '[:upper:]' '[:lower:]')

  if [[ "$FIRST_CHAR" =~ [a-z] ]]; then
    PREFIX="$FIRST_CHAR"
  elif [[ "$FIRST_CHAR" =~ [0-9] ]]; then
    PREFIX="0-9"
  else
    PREFIX="_other"
  fi

  aws s3 cp "$FILE" "s3://${BUCKET}/${PREFIX}/${BASENAME}"
done

Efficient Bulk Sync

For large uploads, stage files with symlinks then use aws s3 sync:

bash

SOURCE_DIR="./files"
STAGING_DIR="./staging"
BUCKET="my-bucket"

# Create staging directory with prefix structure
rm -rf "$STAGING_DIR"
mkdir -p "$STAGING_DIR"

for FILE in "$SOURCE_DIR"/*; do
  [ -f "$FILE" ] || continue
  BASENAME=$(basename "$FILE")
  FIRST_CHAR=$(echo "$BASENAME" | cut -c1 | tr '[:upper:]' '[:lower:]')

  if [[ "$FIRST_CHAR" =~ [a-z] ]]; then
    PREFIX="$FIRST_CHAR"
  elif [[ "$FIRST_CHAR" =~ [0-9] ]]; then
    PREFIX="0-9"
  else
    PREFIX="_other"
  fi

  mkdir -p "$STAGING_DIR/$PREFIX"
  ln -s "$(realpath "$FILE")" "$STAGING_DIR/$PREFIX/$BASENAME"
done

# Sync entire staging directory to S3
aws s3 sync "$STAGING_DIR" "s3://${BUCKET}/"

# Clean up
rm -rf "$STAGING_DIR"

Verification

List files by prefix:

bash

BUCKET="my-bucket"
PREFIX="a"

aws s3 ls "s3://${BUCKET}/${PREFIX}/" --recursive

Generate a manifest of all uploaded files:

bash

BUCKET="my-bucket"

aws s3 ls "s3://${BUCKET}/" --recursive | awk '{print $4}'

Count files per prefix:

bash

BUCKET="my-bucket"

for PREFIX in {a..z} 0-9 _other; do
  COUNT=$(aws s3 ls "s3://${BUCKET}/${PREFIX}/" --recursive 2>/dev/null | wc -l | tr -d ' ')
  [ "$COUNT" -gt 0 ] && echo "$PREFIX: $COUNT files"
done

Error Handling

Common issues and solutions:

Error	Cause	Solution
AccessDenied	Insufficient permissions	Check IAM policy has s3:PutObject on bucket
NoSuchBucket	Bucket doesn't exist	Create bucket or check bucket name spelling
InvalidAccessKeyId	Bad credentials	Verify AWS_ACCESS_KEY_ID is correct
ExpiredToken	Session token expired	Refresh credentials or re-authenticate

Test bucket access before bulk upload:

bash

BUCKET="my-bucket"
echo "test" | aws s3 cp - "s3://${BUCKET}/_test_access.txt" && \
  aws s3 rm "s3://${BUCKET}/_test_access.txt" && \
  echo "Bucket access OK"

Storage Classes

Optimize costs with storage classes:

bash

# Standard (default)
aws s3 cp file.txt s3://bucket/prefix/file.txt

# Infrequent Access (cheaper storage, retrieval fee)
aws s3 cp file.txt s3://bucket/prefix/file.txt --storage-class STANDARD_IA

# Glacier Instant Retrieval (archive with fast access)
aws s3 cp file.txt s3://bucket/prefix/file.txt --storage-class GLACIER_IR

# Intelligent Tiering (auto-optimize based on access patterns)
aws s3 cp file.txt s3://bucket/prefix/file.txt --storage-class INTELLIGENT_TIERING

Add --storage-class to bulk upload loops for cost optimization on infrequently accessed files.