diff --git a/README.md b/README.md
index 9a4c110..0d71fc8 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,8 @@ This project provides examples how to process the Common Crawl dataset with [Apa
 
 + [word count](./word_count.py) (term and document frequency) in Common Crawl's extracted text (WET files)
 
++ [md5](./md5sum.py) Run an external command on entire files from a manifest (WARC, WET, WAT, or any other type of file.)
+
 + [extract links](./wat_extract_links.py) from WAT files and [construct the (host-level) web graph](./hostlinks_to_graph.py) – for further details about the web graphs see the project [cc-webgraph](https://github.com/commoncrawl/cc-webgraph)
 
 + work with the [columnar URL index](https://commoncrawl.org/2018/03/index-to-warc-files-and-urls-in-columnar-format/) (see also [cc-index-table](https://github.com/commoncrawl/cc-index-table) and the notes about [querying the columnar index](#querying-the-columnar-index)):
diff --git a/md5sum.py b/md5sum.py
new file mode 100644
index 0000000..88fe15e
--- /dev/null
+++ b/md5sum.py
@@ -0,0 +1,23 @@
+import subprocess
+import os
+from sparkcc import CCFileProcessorSparkJob
+from pyspark.sql.types import StructType, StructField, StringType
+
+class MD5Sum(CCFileProcessorSparkJob):
+    """ MD5 sum of each file"""
+
+    name = "MD5Sum"
+
+    output_schema = StructType([
+        StructField("uri", StringType(), True),
+        StructField("md5", StringType(), True),
+    ])
+
+    def process_file(self, uri, tempfd):
+        proc = subprocess.run(['md5sum', tempfd.name], capture_output=True, check=True, encoding='utf8')
+        digest = proc.stdout.rstrip().split()[0]
+        yield uri, digest
+
+if __name__ == '__main__':
+    job = MD5Sum()
+    job.run()
diff --git a/sparkcc.py b/sparkcc.py
index 6a99ec9..344c7a6 100644
--- a/sparkcc.py
+++ b/sparkcc.py
@@ -5,7 +5,7 @@
 import re
 
 from io import BytesIO
-from tempfile import SpooledTemporaryFile, TemporaryFile
+from tempfile import SpooledTemporaryFile, TemporaryFile, NamedTemporaryFile
 
 import boto3
 import botocore
@@ -56,7 +56,7 @@ class CCSparkJob(object):
     s3client = None
 
     # pattern to split a data URL (<scheme>://<netloc>/<path> or <scheme>:/<path>)
-    data_url_pattern = re.compile('^(s3|https?|file|hdfs):(?://([^/]*))?/(.*)')
+    data_url_pattern = re.compile('^(s3|https?|file|hdfs|s3a|s3n):(?://([^/]*))?/(.*)')
 
 
     def parse_arguments(self):
@@ -248,7 +248,7 @@ def fetch_warc(self, uri, base_uri=None, offset=-1, length=-1):
 
         stream = None
 
-        if scheme == 's3':
+        if scheme in ['s3', 's3a', 's3n']:
             bucketname = netloc
             if not bucketname:
                 self.get_logger().error("Invalid S3 URI: " + uri)
@@ -621,3 +621,257 @@ def run_job(self, session):
             .saveAsTable(self.args.output)
 
         self.log_accumulators(session)
+
+
+class CCFileProcessorSparkJob(CCSparkJob):
+    """
+    A Spark job definition to process entire files from a manifest.
+    (as opposed to processing individual WARC records)
+    """
+
+    name = 'CCFileProcessor'
+
+    def add_arguments(self, parser):
+        super(CCSparkJob, self).add_arguments(parser)
+        parser.add_argument("--output_base_uri", required=False,
+                            default='./output',
+                            help="Base URI to write output files to. Useful if your job uses write_output_file or check_for_output_file.")
+        
+    def run_job(self, session):
+        input_data = session.sparkContext.textFile(self.args.input,
+                                                   minPartitions=self.args.num_input_partitions)
+
+        output = input_data.mapPartitionsWithIndex(self.process_files) \
+            .reduceByKey(self.reduce_by_key_func)
+
+        session.createDataFrame(output, schema=self.output_schema) \
+            .coalesce(self.args.num_output_partitions) \
+            .write \
+            .format(self.args.output_format) \
+            .option("compression", self.args.output_compression) \
+            .options(**self.get_output_options()) \
+            .saveAsTable(self.args.output)
+
+        self.log_accumulators(session)
+
+    def fetch_file(self, uri, base_uri=None):
+        """
+        Fetch file. This is a modified version of fetch_warc:
+        It does not currently support hdfs, but that could be added if needed.
+        Use NamedTemporaryFile so we can support external tools that require a file path.
+        """
+
+        (scheme, netloc, path) = (None, None, None)
+        uri_match = self.data_url_pattern.match(uri)
+        if not uri_match and base_uri:
+            # relative input URI (path) and base URI defined
+            uri = base_uri + uri
+            uri_match = self.data_url_pattern.match(uri)
+
+        if uri_match:
+            (scheme, netloc, path) = uri_match.groups()
+        else:
+            # keep local file paths as is
+            path = uri
+
+        warctemp = None
+
+        if scheme in ['s3', 's3a', 's3n']:
+            bucketname = netloc
+            if not bucketname:
+                self.get_logger().error("Invalid S3 URI: " + uri)
+                return
+            if not path:
+                self.get_logger().error("Empty S3 path: " + uri)
+                return
+            elif path[0] == '/':
+                # must strip leading / in S3 path
+                path = path[1:]
+            self.get_logger().info('Reading from S3 {}'.format(uri))
+            # download entire file using a temporary file for buffering
+            warctemp = NamedTemporaryFile(mode='w+b', dir=self.args.local_temp_dir)
+            try:
+                self.get_s3_client().download_fileobj(bucketname, path, warctemp)
+                warctemp.flush()
+                warctemp.seek(0)
+            except botocore.client.ClientError as exception:
+                self.get_logger().error(
+                    'Failed to download {}: {}'.format(uri, exception))
+                self.warc_input_failed.add(1)
+                warctemp.close()
+                return
+        elif scheme == 'http' or scheme == 'https':
+            headers = None
+            self.get_logger().info('Fetching {}'.format(uri))
+            response = requests.get(uri, headers=headers)
+
+            if response.ok:
+                # includes "HTTP 206 Partial Content" for range requests
+                warctemp = NamedTemporaryFile(  mode='w+b',
+                                                dir=self.args.local_temp_dir)
+                warctemp.write(response.content)
+                warctemp.flush()
+                warctemp.seek(0)
+            else:
+                self.get_logger().error(
+                    'Failed to download {}: {}'.format(uri, response.status_code))
+                return
+        else:
+            self.get_logger().info('Reading local file {}'.format(uri))
+            if scheme == 'file':
+                # must be an absolute path
+                uri = os.path.join('/', path)
+            else:
+                base_dir = os.path.abspath(os.path.dirname(__file__))
+                uri = os.path.join(base_dir, uri)
+            warctemp = open(uri, 'rb')
+
+        return warctemp
+    
+    def process_files(self, _id, iterator):
+        """Process files, calling process_file(...) for each file"""
+        for uri in iterator:
+            self.warc_input_processed.add(1)
+
+            tempfd = self.fetch_file(uri, self.args.input_base_url)
+            if not tempfd:
+                continue
+
+            for res in self.process_file(uri, tempfd):
+                yield res
+            
+            tempfd.close()
+
+    def process_file(self, uri, tempfd):
+        """Process a single file"""
+        raise NotImplementedError('Processing file needs to be customized')
+    
+    # See if we can get to the bucket referred to in the uri.
+    # note: if uri is not s3, this will return True
+    def validate_s3_bucket_from_uri(self, uri):
+        """
+        Validate that the bucket exists in the S3 URI
+        """
+        if uri is None or len(uri) == 0:
+            return True
+        (scheme, netloc, path) = (None, None, None)
+        uri_match = self.data_url_pattern.match(uri)
+        if uri_match:
+            (scheme, netloc, path) = uri_match.groups()
+        if scheme in ['s3', 's3a', 's3n']:
+            bucketname = netloc
+            if not bucketname:
+                self.get_logger().error("Invalid S3 URI: " + uri)
+                return False
+            try:
+                self.get_s3_client().head_bucket(Bucket=bucketname)
+            except botocore.exceptions.ClientError as e:
+                self.get_logger().error("Failed to access bucket: " + bucketname)
+                return False
+            return True
+        return True
+
+
+    # Like fetch_warc, where we will check if a local file, file on s3, etc exists or not.
+    def check_for_output_file(self, uri, base_uri=None):
+        """
+        Check if output file exists. This is a modified version of fetch_warc:
+        It does not currently support hdfs, but that could be added if needed.
+        """
+        (scheme, netloc, path) = (None, None, None)
+        uri_match = self.data_url_pattern.match(uri)
+        if not uri_match and base_uri:
+            # relative input URI (path) and base URI defined
+            uri = base_uri + uri
+            uri_match = self.data_url_pattern.match(uri)
+        if uri_match:
+            (scheme, netloc, path) = uri_match.groups()
+        else:
+            # keep local file paths as is
+            path = uri
+        if scheme in ['s3', 's3a', 's3n']:
+            bucketname = netloc
+            if not bucketname:
+                self.get_logger().error("Invalid S3 URI: " + uri)
+                return
+            if not path:
+                self.get_logger().error("Empty S3 path: " + uri)
+                return
+            elif path[0] == '/':
+                # must strip leading / in S3 path
+                path = path[1:]
+            self.get_logger().info('Checking if file exists on S3 {}'.format(uri))
+            try:
+                self.get_s3_client().head_object(Bucket=bucketname, Key=path)
+                return True
+            except botocore.client.ClientError as exception:
+                if exception.response['Error']['Code'] == '404':
+                    return False
+                self.get_logger().error(
+                    'Failed to check if file exists on S3 {}: {}'.format(uri, exception))
+                return False
+        elif scheme == 'http' or scheme == 'https':
+            headers = None
+            self.get_logger().info('Checking if file exists {}'.format(uri))
+            response = requests.head(uri, headers=headers)
+            if response.ok:
+                return True
+            else:
+                self.get_logger().error(
+                    'Failed to check if file exists {}: {}'.format(uri, response.status_code))
+                return False
+        else:
+            self.get_logger().info('Checking if local file exists {}'.format(uri))
+            if scheme == 'file':
+                # must be an absolute path
+                uri = os.path.join('/', path)
+            else:
+                base_dir = os.path.abspath(os.path.dirname(__file__))
+                uri = os.path.join(base_dir, uri)
+            return os.path.exists(uri)
+        
+    # like fetch_warc, but will write a file to local, s3, or hdfs
+    def write_output_file(self, uri, fd, base_uri=None):
+        """
+        Write file. This is a modified version of fetch_warc:
+        It does not currently support hdfs, but that could be added if needed.
+        """
+        (scheme, netloc, path) = (None, None, None)
+        uri_match = self.data_url_pattern.match(uri)
+        if not uri_match and base_uri:
+            # relative input URI (path) and base URI defined
+            uri = base_uri + uri
+            uri_match = self.data_url_pattern.match(uri)
+        if uri_match:
+            (scheme, netloc, path) = uri_match.groups()
+        else:
+            # keep local file paths as is
+            path = uri
+        if scheme in ['s3', 's3a', 's3n']:
+            bucketname = netloc
+            if not bucketname:
+                self.get_logger().error("Invalid S3 URI: " + uri)
+                return
+            if not path:
+                self.get_logger().error("Empty S3 path: " + uri)
+                return
+            elif path[0] == '/':
+                # must strip leading / in S3 path
+                path = path[1:]
+            self.get_logger().info('Writing to S3 {}'.format(uri))
+            try:
+                self.get_s3_client().upload_fileobj(fd, bucketname, path)
+            except botocore.client.ClientError as exception:
+                self.get_logger().error(
+                    'Failed to write to S3 {}: {}'.format(uri, exception))
+        else:
+            self.get_logger().info('Writing local file {}'.format(uri))
+            if scheme == 'file':
+                # must be an absolute path
+                uri = os.path.join('/', path)
+            else:
+                base_dir = os.path.abspath(os.path.dirname(__file__))
+                uri = os.path.join(base_dir, uri)
+            os.makedirs(os.path.dirname(uri), exist_ok=True)
+            with open(uri, 'wb') as f:
+                f.write(fd.read())
\ No newline at end of file