This is a script which provides a command line interface for publishing notifications to Amazon SNS.

publishAmazonSNS.sh

#!/bin/bash
#This script creates a command line tool to publish a notification to Amazon SNS.

#The second parameter to urllib.quote is very important here.
#It overrides the default ignore character set which is just '/'
#If the default is set then the strings will not be url encoded to
#Amazon's requirements.
function urlencode {
	python -c "import urllib; print urllib.quote('''$1''', '')"
}

usage="Usage: publishAmazonSNS.sh [options...]
Options:
-a, --awskey	Sets the AWS API Access Key (optional). If not set will read the key from the environment variable $AWSACCESSKEY
-h, --help  	This help text
-k, --awssecretkey	Sets the AWS API Secret Access Key (optional). If not set will read the key from the environment variable $AWSSECRETKEY
-m, --message	Specifies the body of the SNS message (required)
-r, --region	Specfies the region of the AWS SNS Topic to publish the message to (required)
-s, --subject	Specifies the subject of the message (optional)
-t, --topic 	Specfies the AWS SNS Topic to publish the message to (required)
-v, --verbose	Sets the verbosity level. Each instance of -v adds 1 to verbosity"

# Reset all variables that might be set
region=""
topic=""
subject=""
message=""
AWSKey=$AWSACCESSKEY
secretAWSKey=$AWSSECRETKEY
verbose=0

while :
do
    case $1 in
        -h | --help | -\?)
			echo "$usage"
            #  Call your Help() or usage() function here.
            exit 0      # This is not an error, User asked help. Don't do "exit 1"
            ;;
        -r | --region)
			region=$2
			shift 2
			;;
        -t | --topic)
			topic=$2
			shift 2
			;;
        -m | --message)
			message=$2
			shift 2
			;;
        -s | --subject)
			subject=$2
			shift 2
			;;
        -a | --awskey)
			AWSKey=$2
			shift 2
			;;
        -k | --awssecretkey)
			secretAWSKey=$2
			shift 2
			;;
        -v | --verbose)
            # Each instance of -v adds 1 to verbosity
            verbose=$((verbose+1))
            shift
            ;;
        --) # End of all options
            shift
            break
            ;;
        -*)
            echo "WARN: Unknown option (ignored): $1" >&2
            shift
            ;;
        *)  # no more options. Stop while loop
            break
            ;;
    esac
done

# Check for required variables
if [ ! "$region" ]; then
    echo "ERROR: option '--region REGION' not given. See --help" >&2
    exit 1
fi

if [ ! "$topic" ]; then
    echo "ERROR: option '--topic TOPIC' not given. See --help" >&2
    exit 1
fi

if [ ! "$message" ]; then
    echo "ERROR: option '--message MESSAGE' not given. See --help" >&2
    exit 1
fi

if [ ! "$AWSKey" ]; then
    echo "ERROR: neither option '--awskey AWSKEY' given nor environment variable \$AWSACCESSKEY set. See --help" >&2
    exit 1
fi

if [ ! "$secretAWSKey" ]; then
    echo "ERROR: neither option '--awssecretkey AWSSECRETKEY' given nor environment variable \$AWSSECRETKEY set. See --help" >&2
    exit 1
fi

subjectParam=""
if [ "$subject" ]; then
	subjectParam="&Subject=$(urlencode "$subject")"
fi

timestamp=$(date -Iseconds -u)


#ORDER MATTERS!!!!!
#The parameters need to be lexigraphically sorted.
#This means that capitalization makes a difference.
paramString="AWSAccessKeyId=$(urlencode "$AWSKey")\
&Action=Publish\
&Message=$(urlencode "$message")\
&SignatureMethod=HmacSHA256\
&SignatureVersion=2\
$subectParam\
&Timestamp=$(urlencode "$timestamp")\
&TopicArn=$(urlencode "$topic")\
&Version=2010-03-31"

if [ $verbose -ge 1 ]; then
	echo "INFO: Query parameters: $paramString"
fi

stringToSign="POST
sns.$region.amazonaws.com
/
$paramString"

signature=$(echo -n "$stringToSign" | openssl dgst -sha256 -hmac "$secretAWSKey" -binary | base64)
encoded=$(urlencode "$signature")

fullParams="$paramString&Signature=$encoded"

curlVerbose=""
if [ $verbose -ge 2 ]; then
	curlVerbose="-v"
fi

curl $curlVerbose -d "$fullParams" "http://sns.$region.amazonaws.com"