# Digest

The `digest` program returns a message digest for one or more files.

## Example Usage

We list a few examples of the `digest` command here to illustrate its usefulness and ease of use. To get started, lets compute the message digest of these files:

      digest README.txt digest.rdf

Where `digest.rdf` looks something like this:

    <?xml version="1.0"?>
    <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
             xmlns:digest="../digest/1.0/">
      <rdf:Description rdf:about="README.txt">
        <digest:timestamp>2009-01-23T12:25:47-05:00</digest:timestamp>
        <digest:modify-date>2007-08-25T20:19:02-04:00</digest:modify-date>
        <digest:create-date>2007-08-25T20:19:02-04:00</digest:create-date>
        <digest:extent>11476</digest:extent>
        <digest:sha256>78709afc0de69f51085675329dc44c8b475258c1e7fd29acea078347e641a020</digest:sha256>
      </rdf:Description>
    </rdf:RDF>

To determine if any files have been changed, use this command:

      digest -authenticate digest.rdf -

Only files that fail to authenticate are listed. Notice the dash at the end of the command line, a dash means print the output to the terminal.

## Option Summary

The `digest` command recognizes these options. Click on an option to get more details about how that option works.

Option | Description
--- | ---
-authenticate | read message digests from a file and authenticate them
-debug events | display copious debugging information
-hash type | compute the message digest with this hash
-help | print program options
-log format | format of debugging information
-version | print version information