AWS CLI S3 Download Files with Wildcard

The AWS Command Line Interface (AWS CLI) is a powerful tool that allows you to interact with various AWS services directly from your terminal. One of the most common operations in Amazon S3 (Simple Storage Service) is downloading files. When dealing with multiple files that follow a certain naming pattern, using wildcards can significantly simplify the process. This blog post will guide you through the core concepts, typical usage scenarios, common practices, and best practices of using wildcards to download files from an S3 bucket using the AWS CLI.

Table of Contents#

  1. Core Concepts
  2. Typical Usage Scenarios
  3. Common Practice
  4. Best Practices
  5. Conclusion
  6. FAQ
  7. References

Article#

Core Concepts#

Wildcards in AWS CLI S3 Commands#

Wildcards are special characters that represent one or more other characters. In the context of AWS CLI S3 commands, two main wildcards are used:

  • *: This wildcard matches any sequence of zero or more characters. For example, *.txt will match all files with the .txt extension.
  • ?: This wildcard matches exactly one character. For example, file?.txt will match files like file1.txt, file2.txt, etc., but not file.txt or file12.txt.

AWS CLI S3 Download Command#

The basic command to download files from an S3 bucket to your local machine is aws s3 cp. When using wildcards, the command allows you to specify a pattern instead of individual file names. The general syntax is:

aws s3 cp s3://bucket-name/path/to/files/* local-directory/

This command will copy all files that match the pattern from the specified S3 bucket path to the local directory.

Typical Usage Scenarios#

Backup and Recovery#

Suppose you have a large number of log files in an S3 bucket, and you want to back them up to your local machine. You can use wildcards to download all log files at once. For example, if your log files have the naming convention app-log-YYYY-MM-DD.log, you can use the following command to download all log files for a specific month:

aws s3 cp s3://my-logs-bucket/app-log-2023-01-*.log /local/backup/directory/

Data Analysis#

In data analysis, you may need to download a set of data files with a specific extension. For instance, if you have a bucket with both .csv and .json files, and you only want to download the .csv files for analysis, you can use the following command:

aws s3 cp s3://data-bucket/*.csv /local/data-analysis/directory/

Common Practice#

Install and Configure AWS CLI#

Before you can use the AWS CLI to download files from S3, you need to install and configure it. You can install the AWS CLI using the official installation guide for your operating system. After installation, configure the AWS CLI with your AWS access key ID, secret access key, and default region:

aws configure

Download Files with Wildcards#

Once the AWS CLI is configured, you can use the aws s3 cp command with wildcards to download files. Here is an example of downloading all .jpg files from an S3 bucket:

aws s3 cp s3://image-bucket/*.jpg /local/image-directory/

Recursive Download#

If you want to download all files and subdirectories that match a certain pattern, you can use the --recursive option. For example, to download all .pdf files recursively from an S3 bucket:

aws s3 cp s3://document-bucket/ /local/document-directory/ --recursive --exclude "*" --include "*.pdf"

Best Practices#

Error Handling#

When downloading files from S3, it's important to handle errors properly. You can use shell scripting to check the exit status of the aws s3 cp command. For example:

aws s3 cp s3://my-bucket/*.txt /local/txt-directory/
if [ $? -eq 0 ]; then
    echo "Files downloaded successfully."
else
    echo "Error downloading files."
fi

Use Appropriate Permissions#

Make sure that the AWS IAM (Identity and Access Management) user or role associated with your AWS CLI configuration has the necessary permissions to download files from the S3 bucket. You can create an IAM policy that allows the s3:GetObject action on the specific bucket and objects.

Limit the Scope#

When using wildcards, be careful to limit the scope of your downloads. Using a very broad wildcard like * can result in downloading a large number of files, which may consume a lot of bandwidth and storage space. Specify the pattern as precisely as possible.

Conclusion#

Using wildcards with the AWS CLI to download files from an S3 bucket is a powerful and efficient way to handle multiple files at once. It simplifies tasks such as backup, recovery, and data analysis. By understanding the core concepts, typical usage scenarios, common practices, and best practices, software engineers can effectively use wildcards to manage their S3 file downloads.

FAQ#

Q1: Can I use wildcards in the local directory path?#

No, wildcards are only supported in the S3 object key path. You cannot use wildcards in the local directory path when using the aws s3 cp command.

Q2: What if I get a "Permission denied" error when downloading files?#

This error usually indicates that the AWS IAM user or role associated with your AWS CLI configuration does not have the necessary permissions to access the S3 bucket or objects. Check your IAM policy and make sure it allows the s3:GetObject action on the relevant resources.

Q3: How can I see the progress of the file download?#

You can use the --no-progress option to disable the progress bar or omit it to see the progress of the file download. For example:

aws s3 cp s3://my-bucket/*.txt /local/txt-directory/

References#

2025-10