Preparing the environment

Examples in this chapter use cURL for authentication as well as GET, PUT, POST, and DELETE requests run in Bash. To make sending requests easier, you can create the following script ~/.s3_environment, replacing s3_key with S3AcessKeyId and s3_secret with S3SecretAccessKey of a system user:

# S3 login variables.
s3_key="a14040e0b2ef8b28FZZ8"
s3_secret="dbwTnQTW602aAAdq8DQVFzB6yrTCFTNiGB8C8RFA"

# Sign S3 requests and run curl.
function s3_curl() {

    # Parse command line.
    if [ -z "${2}" ]; then
        echo "Usage: ${FUNCNAME[0]} <request_type> <s3_url> [<body_file>]"
        return 1
    fi

    # Prepare a signature.
    s3_url="${2%/*}"
    s3_host="${s3_url##*://}"
    s3_query="${2##*/}"
    s3_date="$(date -R)"

    # Use UNSIGNED-PAYLOAD for the body.
    payload_hash="x-amz-content-sha256:UNSIGNED-PAYLOAD"

    # Generate a signature.
    s3_signature="$(echo -en "${1}\n\n\n${s3_date}\n${payload_hash}\n/${s3_query%%&*}" |\
        openssl dgst -sha1 -hmac ${s3_secret} -binary | base64)"

    content_length="0"
    # Check if a body file is provided.
    if [ -n "${3}" ]; then
        content_length=$(cat ${3} | wc -c )
        body_option="--data-binary @${3}"
    else
        body_option=""
    fi

    # Make the request.
    curl -H "Host: ${s3_host}" \
         -H "Accept: */*" \
         -H "Date: ${s3_date}" \
         -H "${payload_hash}" \
         -H "Authorization: AWS ${s3_key}:${s3_signature}" \
         -H "Content-Type:" \
         -H "Content-Length: ${content_length}" \
         -X "${1}" \
         ${body_option} \
         "${s3_url}/${s3_query}"
}

Load the script into your default environment to make the s3_curl function available.

# source ~/.s3_environment

Once the script is loaded, you can make S3 requests using s3_curl.